PPC: allow --cpu=E500[v2]

Patch by Ancoron Luciferis <ancoron chaoslayer de>

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@21544 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

configure

@@ -1912,6 +1912,14 @@ elif enabled ppc; then
             cpuflags="-mcpu=cell"
             enable ldbrx
         ;;
+        e500v2)
+            cpuflags="-mcpu=8548 -mhard-float -mfloat-gprs=double"
+            disable altivec
+        ;;
+        e500)
+            cpuflags="-mcpu=8540 -mhard-float"
+            disable altivec
+        ;;
     esac
 
 elif enabled x86; then