replace MULL with asm too, no significnat speedup but its probably better to...

replace MULL with asm too, no significnat speedup but its probably better to not take any chances, some versions of gcc will almost certainly mess it up too if they can

Originally committed as revision 6049 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mpegaudiodec.c

@@ -44,7 +44,13 @@
 #define FRAC_ONE    (1 << FRAC_BITS)
 
 #ifdef ARCH_X86
-#   define MULL(a,b) (((int64_t)(a) * (int64_t)(b)) >> FRAC_BITS)
+#   define MULL(ra, rb) \
+        ({ int rt, dummy; asm (\
+            "imull %3               \n\t"\
+            "shrdl %4, %%edx, %%eax \n\t"\
+            : "=a"(rt), "=d"(dummy)\
+            : "a" (ra), "rm" (rb), "i"(FRAC_BITS));\
+         rt; })
 #   define MUL64(ra, rb) \
         ({ int64_t rt; asm ("imull %2\n\t" : "=A"(rt) : "a" (ra), "g" (rb)); rt; })
 #   define MULH(ra, rb) \