contrib/avcodec: pass extra CFLAGS as LDFLAGS on iOS to have the needed flags

(cherry picked from commit f52e54b24015419c09db0c608caeb75232d3206a)

contrib/src/ffmpeg/rules.mak

@@ -101,7 +101,7 @@ FFMPEGCONF += --cpu=core2
 endif
 endif
 ifdef HAVE_IOS
-FFMPEGCONF += --enable-pic
+FFMPEGCONF += --enable-pic --extra-ldflags="$(EXTRA_CFLAGS)"
 ifdef HAVE_NEON
 FFMPEGCONF += --as="$(AS)"
 endif