libpci: djgpp: Allow to specify empty IDSDIR=

Like for windows builds this will cause to load pci.ids file from the same
directory where is stored application binary. Code is same as for Windows,
just djgpp uses global symbol __dos_argv0 instead of _pgmptr.

Tested with following compile command:
  make CROSS_COMPILE=i586-pc-msdosdjgpp- HOST=i586-djgpp ZLIB=no DNS=no IDSDIR=

1 files changed, 11 insertions, 3 deletions

diff --git a/lib/init.c b/lib/init.c
index 590dfb4..8c8f973 100644
--- a/lib/init.c
+++ b/lib/init.c
@@ -13,6 +13,10 @@
 
 #include "internal.h"
 
+#ifdef PCI_OS_DJGPP
+#include <crt0.h> /* for __dos_argv0 */
+#endif
+
 #ifdef PCI_OS_WINDOWS
 
 #include <windows.h>
@@ -262,7 +266,7 @@ pci_get_method_name(int index)
     return pci_methods[index]->name;
 }
 
-#ifdef PCI_OS_WINDOWS
+#if defined(PCI_OS_WINDOWS) || defined(PCI_OS_DJGPP)
 
 static void
 pci_init_name_list_path(struct pci_access *a)
@@ -274,7 +278,7 @@ pci_init_name_list_path(struct pci_access *a)
       char *path, *sep;
       size_t len;
 
-#if defined(_WIN32) || defined(_WINDLL) || defined(_WINDOWS)
+#if defined(PCI_OS_WINDOWS) && (defined(_WIN32) || defined(_WINDLL) || defined(_WINDOWS))
 
       HMODULE module;
       size_t size;
@@ -309,11 +313,15 @@ retry:
       else if (len == 0)
         path[0] = '\0';
 
-#else
+#elif defined(PCI_OS_DJGPP) || defined(PCI_OS_WINDOWS)
 
       const char *exe_path;
 
+#ifdef PCI_OS_DJGPP
+      exe_path = __dos_argv0;
+#else
       exe_path = _pgmptr;
+#endif
 
       len = strlen(exe_path);
       path = pci_malloc(a, len+sizeof(PCI_IDS));