Support amdfam10 for --cpu, also avoids a warning about unknown cpu if

--cpu=host is used on AMD Phenom and newer at least.

Originally committed as revision 20367 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1675,7 +1675,7 @@ case $cpu in
         disable cmov
     ;;
     # targets that do support conditional mov (cmov)
-    i686|pentiumpro|pentium[23]|pentium-m|athlon|athlon-tbird|athlon-4|athlon-[mx]p|athlon64|k8|opteron|athlon-fx|core2)
+    i686|pentiumpro|pentium[23]|pentium-m|athlon|athlon-tbird|athlon-4|athlon-[mx]p|athlon64|k8|opteron|athlon-fx|core2|amdfam10)
         cpuflags="-march=$cpu"
         enable cmov
         enable fast_cmov