Disable MMX for i686 and pentiumpro

Originally committed as revision 24946 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -2105,8 +2105,14 @@ elif enabled x86; then
             cpuflags="-march=$cpu"
             disable cmov
         ;;
+        i686|pentiumpro)
+            cpuflags="-march=$cpu"
+            enable cmov
+            enable fast_cmov
+            disable mmx
+        ;;
         # targets that do support conditional mov (cmov)
-        i686|pentiumpro|pentium[23]|pentium-m|athlon|athlon-tbird|athlon-4|athlon-[mx]p|athlon64|k8|opteron|athlon-fx|core2|amdfam10|barcelona|atom)
+        pentium[23]|pentium-m|athlon|athlon-tbird|athlon-4|athlon-[mx]p|athlon64|k8|opteron|athlon-fx|core2|amdfam10|barcelona|atom)
             cpuflags="-march=$cpu"
             enable cmov
             enable fast_cmov