avfilter/vf_vif: Remove superfluous ';'

Inside a function a superfluous ';' is just a null-statement; yet
outside it is invalid, even though compilers happen to accept them.
They (at least GCC and Clang) only warn about this when on -pedantic.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavfilter/vf_vif.c

@@ -429,8 +429,8 @@ static void offset_##bits##bit(VIFContext *s,            \
     } \
 }
 
-offset_fn(uint8_t, 8);
+offset_fn(uint8_t, 8)
-offset_fn(uint16_t, 10);
+offset_fn(uint16_t, 10)
 
 static void set_meta(AVDictionary **metadata, const char *key, float d)
 {