On modern distributions, ld runs with the '--as-needed' option
enabled by default, meaning library dependencies must come after
files that require them. Also, this allows indirect linking so the
build commands can be simplified.

The alternative is to add the '-Wl,--no-as-needed' gcc option or
use the top-level Makefile.

Tested on:
 * Ubuntu 16.04.3 with gcc Ubuntu 5.4.1-8ubuntu1
 * Fedora 24 with gcc Red Hat 6.1.1-3

Signed-off-by: Lucas Magasweran <lucas.magasweran@ieee.org>

https://mail.gnome.org/archives/networkmanager-list/2017-September/msg00022.html
https://mail.gnome.org/archives/networkmanager-list/2017-September/msg00023.html
https://mail.gnome.org/archives/networkmanager-list/2017-September/msg00025.html

	cat <<-EOF > /tmp/glib-mkenums
	#!/bin/bash
	sleep 15 && /usr/bin/glib-mkenums "\$@"
	EOF

	chmod +x /tmp/glib-mkenums

	(export PATH="/tmp:$PATH" &&
	 git clean -fdx &&
	 ./autogen.sh &&
	 make -j20 all-am)

(cherry picked from commit 68ab166f3894834af9473d42f5dab72e0ed15394)

In practice, this should only matter when there are multiple
header files with the same name. That is something we try
to avoid already, by giving headers a distinct name.

When building NetworkManager itself, we clearly want to use
double-quotes for including our own headers.
But we also want to do that in our public headers. For example:

  ./a.c
    #include <stdio.h>
    #include <nm-1.h>
    void main() {
        printf ("INCLUDED %s/nm-2.h\n", SYMB);
    }

  ./1/nm-1.h
    #include <nm-2.h>

  ./1/nm-2.h
    #define SYMB "1"

  ./2/nm-2.h
    #define SYMB "2"

$ cc -I./2 -I./1 ./a.c
$ ./a.out
INCLUDED 2/nm-2.h

Exceptions to this are
  - headers in "shared/nm-utils" that include <NetworkManager.h>. These
    headers are copied into projects and hence used like headers owned by
    those projects.
  - examples/C

Reported-by: Ali Nematollahi <alirezan1@gmail.com>

- All internal source files (except "examples", which are not internal)
  should include "config.h" first. As also all internal source
  files should include "nm-default.h", let "config.h" be included
  by "nm-default.h" and include "nm-default.h" as first in every
  source file.
  We already wanted to include "nm-default.h" before other headers
  because it might contains some fixes (like "nm-glib.h" compatibility)
  that is required first.

- After including "nm-default.h", we optinally allow for including the
  corresponding header file for the source file at hand. The idea
  is to ensure that each header file is self contained.

- Don't include "config.h" or "nm-default.h" in any header file
  (except "nm-sd-adapt.h"). Public headers anyway must not include
  these headers, and internal headers are never included after
  "nm-default.h", as of the first previous point.

- Include all internal headers with quotes instead of angle brackets.
  In practice it doesn't matter, because in our public headers we must
  include other headers with angle brackets. As we use our public
  headers also to compile our interal source files, effectively the
  result must be the same. Still do it for consistency.

- Except for <config.h> itself. Include it with angle brackets as suggested by
  https://www.gnu.org/software/autoconf/manual/autoconf.html#Configuration-Headers

Up to now, the "include" directory contained (only) header files that were
used project-wide by libs, core, clients, et al.

Since the directory now also contains a non-header file, the "include"
name is misleading. Instead of adding yet another directory that is
project-wide, with non-header-only content, rename the "include"
directory to "shared".

For libnm library, "nm-dbus-interface.h" contains defines like the D-Bus
paths of NetworkManager. It is desirable to have this header usable without
having a dependency on "glib.h", for example for a QT application. For that,
commit c0852964a890cf43cc2dcaeff41ac6edc5028f24 removed that dependancy.

For libnm-glib library, the analog to "nm-dbus-interface.h" is
"NetworkManager.h", and the same applies there. Commit
159e827a72f420048e12d318f8ba1edd3f641fc8 removed that include.
However, that broke build on PackageKit [1] which expected to get the
version macros by including "NetworkManager.h". So at least for libnm-glib,
we need to preserve old behavior so that a user including
"NetworkManager.h" gets the version macros, but not "glib.h".

Extract the version macros to a new header file "nm-version-macros.h".
This header doesn't include "glib.h" and can be included from
"NetworkManager.h". This gives as previous behavior and a glib-free
include.

For libnm we still don't include "nm-version-macros.h" to "nm-dbus-interface.h".
Very few users will actually need the version macros, but not using
libnm.
Users that use libnm, should just include (libnm's) "NetworkManager.h" to
get all headers.
As a special case, a user who doesn't want to use glib/libnm, but still
needs both "nm-dbus-interface.h" and "nm-version-macros.h", can include
them both separately.

[1] https://github.com/hughsie/PackageKit/issues/85

Fixes: 4545a7fe9670ce4d7c259c11c2cc853bfae6729b