Use MIXCALL and MIXCALLCC for own API

When library is built as VB6 binding, the function call pointers conflict
gets resulted when attempting to set the function pointer into SDL2 api
that still use own SDLCALL variant. So, keep all function pointers use default
SDLCALL, but MixerX's API will use MIXCALL which will OR equal to SDLCALL, OR
will use own setup when VB6 mode is enabled.

VB6_Wrapper/vb6_sdl_binds.c

@@ -44,44 +44,44 @@ extern DECLSPEC int SDL_Init(Uint32 flags);
 extern DECLSPEC void SDL_Quit();
 extern DECLSPEC const char * SDL_GetError(void);
 
-__declspec(dllexport) int SDLCALLCC SDL_InitAudio(void)
+__declspec(dllexport) int MIXCALLCC SDL_InitAudio(void)
 {
     return SDL_Init(SDL_INIT_AUDIO);
 }
 
-__declspec(dllexport) void SDLCALLCC SDL_QuitVB6(void)
+__declspec(dllexport) void MIXCALLCC SDL_QuitVB6(void)
 {
     SDL_Quit();
 }
 
-__declspec(dllexport) int SDLCALLCC Mix_InitVB6(void)
+__declspec(dllexport) int MIXCALLCC Mix_InitVB6(void)
 {
     return Mix_Init(0);
 }
 
-__declspec(dllexport) int SDLCALLCC Mix_OpenAudioVB6(int frequency, int format, int channels, int chunksize)
+__declspec(dllexport) int MIXCALLCC Mix_OpenAudioVB6(int frequency, int format, int channels, int chunksize)
 {
     return Mix_OpenAudio(frequency, (Uint16)format, channels, chunksize);
 }
 
-__declspec(dllexport) Mix_Chunk * SDLCALLCC Mix_LoadWAV_VB6(const char*file)
+__declspec(dllexport) Mix_Chunk * MIXCALLCC Mix_LoadWAV_VB6(const char*file)
 {
     return Mix_LoadWAV_RW(SDL_RWFromFile(file, "rb"), 1);
 }
 
-__declspec(dllexport) const char* SDLCALLCC SDL_GetErrorVB6(void)
+__declspec(dllexport) const char* MIXCALLCC SDL_GetErrorVB6(void)
 {
     return SDL_GetError();
 }
 
 /* SDL RWops*/
 
-__declspec(dllexport) SDL_RWops * SDLCALLCC SDL_RWFromFileVB6(const char *file, const char *mode)
+__declspec(dllexport) SDL_RWops * MIXCALLCC SDL_RWFromFileVB6(const char *file, const char *mode)
 {
     return SDL_RWFromFileVB6(file, mode);
 }
 
-__declspec(dllexport) SDL_RWops * SDLCALLCC SDL_RWFromMemVB6(void *mem, int size)
+__declspec(dllexport) SDL_RWops * MIXCALLCC SDL_RWFromMemVB6(void *mem, int size)
 {
     return SDL_RWFromMem(mem, size);
 }
@@ -91,42 +91,42 @@ __declspec(dllexport) SDL_RWops * SDL_AllocRWVB6(void)
     return SDL_AllocRW();
 }
 
-__declspec(dllexport) void SDLCALLCC SDL_FreeRWVB6(SDL_RWops * area)
+__declspec(dllexport) void MIXCALLCC SDL_FreeRWVB6(SDL_RWops * area)
 {
     SDL_FreeRW(area);
 }
 
-__declspec(dllexport) int SDLCALLCC SDL_RWsizeVB6(SDL_RWops * ctx)
+__declspec(dllexport) int MIXCALLCC SDL_RWsizeVB6(SDL_RWops * ctx)
 {
     return (int)(ctx)->size(ctx);
 }
 
-__declspec(dllexport) int SDLCALLCC SDL_RWseekVB6(SDL_RWops * ctx, int offset, int whence)
+__declspec(dllexport) int MIXCALLCC SDL_RWseekVB6(SDL_RWops * ctx, int offset, int whence)
 {
     return (int)(ctx)->seek(ctx, offset, whence);
 }
 
-__declspec(dllexport) int SDLCALLCC SDL_RWtellVB6(SDL_RWops * ctx)
+__declspec(dllexport) int MIXCALLCC SDL_RWtellVB6(SDL_RWops * ctx)
 {
     return (int)(ctx)->seek(ctx, 0, RW_SEEK_CUR);
 }
 
-__declspec(dllexport) int SDLCALLCC SDL_RWreadVB6(SDL_RWops * ctx, void*ptr, int size, int maxnum)
+__declspec(dllexport) int MIXCALLCC SDL_RWreadVB6(SDL_RWops * ctx, void*ptr, int size, int maxnum)
 {
     return (int)(ctx)->read(ctx, ptr, size, maxnum);
 }
 
-__declspec(dllexport) int SDLCALLCC SDL_RWwriteVB6(SDL_RWops * ctx, void* ptr, int size, int maxnum)
+__declspec(dllexport) int MIXCALLCC SDL_RWwriteVB6(SDL_RWops * ctx, void* ptr, int size, int maxnum)
 {
     return (int)(ctx)->write(ctx, ptr, size, maxnum);
 }
 
-__declspec(dllexport) int SDLCALLCC SDL_RWcloseVB6(SDL_RWops * ctx)
+__declspec(dllexport) int MIXCALLCC SDL_RWcloseVB6(SDL_RWops * ctx)
 {
     return (int)(ctx)->close(ctx);
 }
 
-__declspec(dllexport) const char* SDLCALLCC MIX_ADLMIDI_getBankName(int bankID)
+__declspec(dllexport) const char* MIXCALLCC MIX_ADLMIDI_getBankName(int bankID)
 {
     return Mix_ADLMIDI_getBankNames()[bankID];
 }