ARM: change MUL16() macro to inline function

Originally committed as revision 15783 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/armv4l/mathops.h

@@ -82,10 +82,13 @@ static inline av_const int64_t MAC64(int64_t d, int a, int b)
     __asm__ ("smlabb %0, %1, %2, %0" : "+r"(rt) : "r"(ra), "r"(rb));
 
 /* signed 16x16 -> 32 multiply */
-#   define MUL16(ra, rb)                                                \
-        ({ int rt;                                                    \
-         __asm__ ("smulbb %0, %1, %2" : "=r" (rt) : "r" (ra), "r" (rb));  \
-         rt; })
+#   define MUL16 MUL16
+static inline av_const MUL16(int ra, int rb)
+{
+    int rt;
+    __asm__ ("smulbb %0, %1, %2" : "=r"(rt) : "r"(ra), "r"(rb));
+    return rt;
+}
 
 #endif