Makefile.m32: deduplicate build rules [ci skip]

After this patch, we reduce the three copies of most `Makefile.m32`
logic to one. This now resides in `lib/Makefile.m32`. It makes future
updates easier, the code shorter, with a small amount of added
complexity.

`Makefile.m32` reduction:

|                   |  bytes | LOC total |  blank |  comment |  code |
|-------------------|-------:|----------:|-------:|---------:|------:|
| 7.85.0            |  34772 |      1337 |     79 |      192 |  1066 |
| before this patch |  17601 |       625 |     62 |      106 |   457 |
| after this patch  |  11680 |       392 |     52 |      104 |   236 |

Details:

- Change rules to create objects for the `v*` subdirs in the `lib` dir.
  This allows to use a shared compile rule and assumes that filenames
  are not (and will not be) colliding across these directories.
  `Makefile.m32` now also stores a list of these subdirs. They are
  changing rarely though.

- Sync as much as possible between the three `Makefile.m32` scripts'
  rules and their source/target sections.

- After this patch `CPPFLAGS` are all applied to the `src` sources once
  again. This matches the behaviour of cmake/autotools. Only zlib ones
  are actually required there.

- Use `.rc` names from `Makefile.inc` instead of keeping a duplicate.

- Change examples to link `libcurl.dll` by default. This makes building
  trivial, even as a cross-build:
    `CC=x86_64-w64-mingw32-gcc make -f Makefile.m32`
  To run them, you need to move/copy or add-to-path `libcurl.dll`.
  You can select static mode via `CFG=-static`.

- List more of the `Makefile.m32` config variables.

- Drop `.rc` support from examples. It made it fragile without much
  benefit.

- Include a necessary system lib for the `externalsocket.c` example.

- Exclude unnecessary systems libs when building in `-dyn` mode.

Closes #9642

1 files changed, 13 insertions, 142 deletions

diff --git a/src/Makefile.m32 b/src/Makefile.m32
index 01dc30cb0..298fc8acc 100644
--- a/src/Makefile.m32
+++ b/src/Makefile.m32
@@ -22,173 +22,44 @@
 #
 #***************************************************************************
 
-# Makefile for building curl with MinGW and optional features.
-#
-# Usage:   mingw32-make -f Makefile.m32 CFG=-feature1[-feature2][-feature3][...]
-# Example: mingw32-make -f Makefile.m32 CFG=-zlib-ssl-sspi-winidn
-#
-# Set component roots via envvar <feature>_PATH. CPPFLAGS, LDFLAGS, LIBS,
-# CFLAGS, RCFLAGS (and more) are also available for customization.
+# See usage in lib/Makefile.m32
 
 PROOT := ..
 
-CPPFLAGS += -I. -I$(PROOT)/include -I$(PROOT)/lib
-RCFLAGS  += -I$(PROOT)/include -DCURL_EMBED_MANIFEST
+RCFLAGS  += -DCURL_EMBED_MANIFEST
+CPPFLAGS += -I$(PROOT)/lib
 LDFLAGS  += -L$(PROOT)/lib
 LIBS     += -lcurl
 
-ifneq ($(ARCH),custom)
-  # Set environment var ARCH to your architecture to override autodetection.
-  ifndef ARCH
-    ifneq ($(findstring x86_64,$(shell $(CC) -dumpmachine)),)
-      ARCH := w64
-    else
-      ARCH := w32
-    endif
-  endif
-  ifeq ($(ARCH),w64)
-    CFLAGS  += -m64
-    LDFLAGS += -m64
-    RCFLAGS += --target=pe-x86-64
-  else
-    CFLAGS  += -m32
-    LDFLAGS += -m32
-    RCFLAGS += --target=pe-i386
-  endif
-endif
-
-### Optional features
-
 ifneq ($(findstring -dyn,$(CFG)),)
   curl_DEPENDENCIES := $(PROOT)/lib/libcurl$(CURL_DLL_SUFFIX).dll
   curl_DEPENDENCIES += $(PROOT)/lib/libcurl.dll.a
+  DYN := 1
 else
   curl_DEPENDENCIES := $(PROOT)/lib/libcurl.a
   CPPFLAGS += -DCURL_STATICLIB
   LDFLAGS += -static
 endif
 
-ifneq ($(findstring -unicode,$(CFG)),)
-  CPPFLAGS += -DUNICODE -D_UNICODE
-  LDFLAGS += -municode
-endif
-ifneq ($(findstring -sync,$(CFG)),)
-else
-  ifneq ($(findstring -ares,$(CFG)),)
-    LIBCARES_PATH ?= $(PROOT)/../c-ares
-    LDFLAGS += -L"$(LIBCARES_PATH)/lib"
-    LIBS += -lcares
-  endif
-endif
-ifneq ($(findstring -rtmp,$(CFG)),)
-  LIBRTMP_PATH ?= $(PROOT)/../librtmp
-  LDFLAGS += -L"$(LIBRTMP_PATH)/librtmp"
-  LIBS += -lrtmp -lwinmm
-  ZLIB := 1
-endif
-ifneq ($(findstring -ssh2,$(CFG)),)
-  LIBSSH2_PATH ?= $(PROOT)/../libssh2
-  LDFLAGS += -L"$(LIBSSH2_PATH)/lib"
-  LDFLAGS += -L"$(LIBSSH2_PATH)/win32"
-  LIBS += -lssh2
-endif
-ifneq ($(findstring -nghttp2,$(CFG)),)
-  NGHTTP2_PATH ?= $(PROOT)/../nghttp2
-  LDFLAGS += -L"$(NGHTTP2_PATH)/lib"
-  LIBS += -lnghttp2
-endif
-ifneq ($(findstring -nghttp3,$(CFG)),)
-  ifneq ($(findstring -ngtcp2,$(CFG)),)
-    NGHTTP3_PATH ?= $(PROOT)/../nghttp3
-    LDFLAGS += -L"$(NGHTTP3_PATH)/lib"
-    LIBS += -lnghttp3
-    NGTCP2_PATH ?= $(PROOT)/../ngtcp2
-    LDFLAGS += -L"$(NGTCP2_PATH)/lib"
-    NGTCP2_LIBS ?= -lngtcp2 -lngtcp2_crypto_openssl
-    LIBS += $(NGTCP2_LIBS)
-  endif
-endif
-ifneq ($(findstring -ssl,$(CFG)),)
-  OPENSSL_PATH ?= $(PROOT)/../openssl
-  OPENSSL_LIBPATH ?= $(OPENSSL_PATH)/lib
-  LDFLAGS += -L"$(OPENSSL_LIBPATH)"
-  OPENSSL_LIBS ?= -lssl -lcrypto
-  LIBS += $(OPENSSL_LIBS)
-endif
-ifneq ($(findstring -zlib,$(CFG))$(ZLIB),)
-  ZLIB_PATH ?= $(PROOT)/../zlib
-  CPPFLAGS += -DHAVE_LIBZ -DHAVE_ZLIB_H
-  CPPFLAGS += -I"$(ZLIB_PATH)"
-  LDFLAGS += -L"$(ZLIB_PATH)"
-  LIBS += -lz
-endif
-ifneq ($(findstring -zstd,$(CFG)),)
-  ZSTD_PATH ?= $(PROOT)/../zstd
-  LDFLAGS += -L"$(ZSTD_PATH)/lib"
-  ZSTD_LIBS ?= -lzstd
-  LIBS += $(ZSTD_LIBS)
-endif
-ifneq ($(findstring -brotli,$(CFG)),)
-  BROTLI_PATH ?= $(PROOT)/../brotli
-  LDFLAGS += -L"$(BROTLI_PATH)/lib"
-  BROTLI_LIBS ?= -lbrotlidec -lbrotlicommon
-  LIBS += $(BROTLI_LIBS)
-endif
-ifneq ($(findstring -gsasl,$(CFG)),)
-  LIBGSASL_PATH ?= $(PROOT)/../gsasl
-  LDFLAGS += -L"$(LIBGSASL_PATH)/lib"
-  LIBS += -lgsasl
-endif
-ifneq ($(findstring -idn2,$(CFG)),)
-  LIBIDN2_PATH ?= $(PROOT)/../libidn2
-  LDFLAGS += -L"$(LIBIDN2_PATH)/lib"
-  LIBS += -lidn2
-else
-ifneq ($(findstring -winidn,$(CFG)),)
-  LIBS += -lnormaliz
-endif
-endif
-ifeq ($(findstring -lldap,$(LIBS)),)
-  LIBS += -lwldap32
-endif
-LIBS += -lws2_32 -lcrypt32 -lbcrypt
-
 ### Sources and targets
 
-# Provides CURL_CFILES and CURLX_CFILES
+# Provides CURL_CFILES, CURLX_CFILES, CURL_RCFILES
 include Makefile.inc
 
 TARGETS := curl.exe
+
 curl_OBJECTS := $(patsubst %.c,%.o,$(strip $(CURL_CFILES)))
 curl_OBJECTS += $(patsubst %.c,%.o,$(notdir $(strip $(CURLX_CFILES))))
+curl_OBJECTS += $(patsubst %.rc,%.res,$(strip $(CURL_RCFILES)))
 vpath %.c $(PROOT)/lib
 
-RESOURCE := curl.res
-
-### Rules
-
-CC ?= $(CROSSPREFIX)gcc
-RC ?= $(CROSSPREFIX)windres
-
-ifneq ($(findstring /sh,$(SHELL)),)
-DEL = rm -f $1
-else
-DEL = -del 2>NUL /q /f $(subst /,\,$1)
-endif
-
-all: $(TARGETS)
-
-$(TARGETS): $(curl_OBJECTS) $(RESOURCE) $(curl_DEPENDENCIES)
-	$(CC) $(LDFLAGS) $(CURL_LDFLAGS_BIN) -o $@ $(curl_OBJECTS) $(RESOURCE) $(LIBS)
+TOCLEAN := $(curl_OBJECTS)
 
-%.o: %.c
-	$(CC) $(CFLAGS) $(CPPFLAGS) -c $<
+### Local rules
 
-%.res: %.rc
-	$(RC) -O coff $(RCFLAGS) -i $< -o $@
+$(TARGETS): $(curl_OBJECTS) $(curl_DEPENDENCIES)
+	$(CC) $(LDFLAGS) $(CURL_LDFLAGS_BIN) -o $@ $(curl_OBJECTS) $(LIBS)
 
-clean:
-	@$(call DEL, $(curl_OBJECTS) $(RESOURCE))
+### Global script
 
-distclean vclean: clean
-	@$(call DEL, $(TARGETS))
+include $(PROOT)/lib/Makefile.m32