remove old msvc cruft

Originally committed as revision 5735 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavutil/common.h

@@ -94,14 +94,8 @@
     typedef unsigned char  uint8_t;
     typedef unsigned short uint16_t;
     typedef unsigned int   uint32_t;
-
-#   ifdef __MINGW32__
-        typedef signed __int64   int64_t;
-        typedef unsigned __int64 uint64_t;
-#   else /* other OS */
     typedef signed long long   int64_t;
     typedef unsigned long long uint64_t;
-#   endif /* other OS */
 #endif /* EMULATE_INTTYPES */
 
 #ifndef PRId64