configure: Check for support for labels in the inline assembly

Use this for enabling the ppc timer.h implementation only on
assemblers that support labels in the inline assembly.

Signed-off-by: Martin Storsjö <martin@martin.st>

libavutil/ppc/timer.h

@@ -23,6 +23,10 @@
 
 #include <stdint.h>
 
+#include "config.h"
+
+#if HAVE_INLINE_ASM_LABELS
+
 #define AV_READ_TIME read_time
 
 static inline uint64_t read_time(void)
@@ -44,4 +48,6 @@ static inline uint64_t read_time(void)
      return (((uint64_t)tbu)<<32) | (uint64_t)tbl;
 }
 
+#endif /* HAVE_INLINE_ASM_LABELS */
+
 #endif /* AVUTIL_PPC_TIMER_H */