avfilter/vf_pullup: workaround bug in gcc 4.4.3 on ARM

The gcc version affected is very old and unmaintained AFAIK thus i made no
attempt to report this to the gcc developers.

The workaround is pushed as it may still affect users and does affect one
fate client
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/vf_pullup.c

@@ -67,7 +67,7 @@ static int query_formats(AVFilterContext *ctx)
     return 0;
 }
 
-#define ABS(a) (((a) ^ ((a) >> 31)) - ((a) >> 31))
+#define ABS(a) ((a) > 0 ? (a) : -(a))
 
 static int diff_c(const uint8_t *a, const uint8_t *b, ptrdiff_t s)
 {