Compiling libgd on WinXP/MinGW/MSYS

I have a WinXP machine running MinGW/MSYS, and I was having a tough
time getting libgd to compile. The message "symbol lacks external
linkage" kept popping up. I did some poking around on the Internet and
found that it had something do with the 'dllimport' attribute on
function calls.

http://www.google.com/search?ie=UTF-8&oe=utf-8&q=%22symbol+lacks+external+linkage%22&qt_s=Search&sa=N&tab=gw

I eventually landed here --

http://www.phpman.info/index.php/info/gcc

-- and after some tinkering, made a little hack that worked to get it
to compile. I can't really explain why it works (my notion of vtables
and system handling of library function export/imports is hazy, I'm
afraid), but I thought it might be useful to note for users building
libgd with this particular config. Also, I thought the maintainers may
have a clearer idea about what's going on, and provide a better hack
to accommodate the MinGW environments.

My hack was as follows:

----- Makefile:
DEFS = -DHAVE_CONFIG_H -DMINGW


----- gd.h:
#ifdef MINGW       // Declare macros this way...

#define BGD_DECLARE(rt) __declspec(dllexport) rt __stdcall
#define BGD_EXPORT_DATA_PROT __declspec(dllexport) extern
#define BGD_EXPORT_DATA_IMPL __declspec(dllexport)

#else       // If not MINGW, then do defines the  original way

#ifdef NONDLL
#define BGD_DECLARE(rt) extern rt
#else
#ifdef BGDWIN32
#define BGD_DECLARE(rt) __declspec(dllexport) rt __stdcall
#else
#define BGD_DECLARE(rt) __declspec(dllimport) rt _stdcall
#endif // BGDWIN32
#endif // NONDLL

/* 2.0.20: for actual storage of exported data, functions don't need this,
  currently needed only for font pointers */
#ifdef NONDLL
// 2.0.25: bring back extern
#define BGD_EXPORT_DATA_PROT extern
#define BGD_EXPORT_DATA_IMPL
#else
#ifdef BGDWIN32
#define BGD_EXPORT_DATA_PROT __declspec(dllexport) extern
#define BGD_EXPORT_DATA_IMPL __declspec(dllexport)
#else
#define BGD_EXPORT_DATA_PROT __declspec(dllimport) extern
#define BGD_EXPORT_DATA_IMPL __declspec(dllimport)
#endif // BGDWIN32
#endif // NONDLL

#endif // MINGW


Cheers, JA