ffmpeg: add upstream patches fixing MIPS compilation

Removed the Makefile references.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

multimedia/ffmpeg/patches/030-h264-mips.patch

@@ -0,0 +1,16 @@
+--- a/libavcodec/mips/cabac.h
++++ b/libavcodec/mips/cabac.h
+@@ -28,6 +28,7 @@
+ #include "libavutil/mips/mmiutils.h"
+ #include "config.h"
+ 
++#ifndef __mips16
+ #define get_cabac_inline get_cabac_inline_mips
+ static av_always_inline int get_cabac_inline(CABACContext *c,
+                                              uint8_t * const state){
+@@ -116,4 +117,5 @@ static av_always_inline int get_cabac_inline(CABACContext *c,
+     return bit;
+ }
+ 
++#endif
+ #endif /* AVCODEC_MIPS_CABAC_H */