h264: move h264_mvpred.h include.

Fixes the following compile error with darwin/gcc-4.2.1:
In file included from libavcodec/error_resilience.c:33:
libavcodec/h264.h: In function ‘decode_mb_skip’:
libavcodec/h264.h:773: error: ‘always_inline’ function could not be inlined in call to ‘pred_pskip_motion’: the function body must appear before caller
libavcodec/h264.h:1334: error: called from here

libavcodec/h264.h

@@ -770,7 +770,7 @@ static av_always_inline int get_chroma_qp(H264Context *h, int t, int qscale){
     return h->pps.chroma_qp_table[t][qscale];
 }
 
-static av_always_inline void pred_pskip_motion(H264Context * const h);
+#include "h264_mvpred.h" //For pred_pskip_motion()
 
 static void fill_decode_neighbors(H264Context *h, int mb_type){
     MpegEncContext * const s = &h->s;
@@ -1341,6 +1341,4 @@ static void av_unused decode_mb_skip(H264Context *h){
     h->prev_mb_skipped= 1;
 }
 
-#include "h264_mvpred.h" //For pred_pskip_motion()
-
 #endif /* AVCODEC_H264_H */