ARM: dca: disable optimised decode_blockcodes() for old gcc

Old gcc versions have trouble compiling this function, and
no simple, targeted test is possible.

Signed-off-by: Mans Rullgard <mans@mansr.com>

libavcodec/arm/dca.h

@@ -25,7 +25,7 @@
 #include "config.h"
 #include "libavutil/intmath.h"
 
-#if HAVE_ARMV6 && HAVE_INLINE_ASM
+#if HAVE_ARMV6 && HAVE_INLINE_ASM && AV_GCC_VERSION_AT_LEAST(4,4)
 
 #define decode_blockcodes decode_blockcodes
 static inline int decode_blockcodes(int code1, int code2, int levels,