__stdcall -> WINAPI

Windows x64 has no __stdcall.
It is not yet supported, but someday it might...

Originally committed as revision 12363 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/w32thread.c

@@ -36,7 +36,7 @@ typedef struct ThreadContext{
 }ThreadContext;
 
 
-static unsigned __stdcall attribute_align_arg thread_func(void *v){
+static unsigned WINAPI attribute_align_arg thread_func(void *v){
     ThreadContext *c= v;
 
     for(;;){

libavformat/os_support.h

@@ -32,7 +32,7 @@ typedef int socklen_t;
 #endif
 
 #ifdef __MINGW32__
-__declspec(dllimport) void __stdcall Sleep(unsigned long dwMilliseconds);
+__declspec(dllimport) void WINAPI Sleep(unsigned long dwMilliseconds);
 // #  include <windows.h>
 #  define usleep(t)    Sleep((t) / 1000)
 #  include <fcntl.h>