build PIC code on powerpc

this avoids failing 24bit relocations as seen on
http://bugs.debian.org/561956 as side effect


Originally committed as revision 21613 to svn://svn.ffmpeg.org/ffmpeg/branches/0.5

configure

@@ -2219,7 +2219,7 @@ if enabled shared; then
     # LIBOBJFLAGS may have already been set in the OS configuration
     if test -z "$LIBOBJFLAGS" ; then
         case "${subarch-$arch}" in
-            x86_64|ia64|alpha|sparc*|power*|parisc*|mips*) LIBOBJFLAGS='$(PIC)' ;;
+            x86_64|ia64|alpha|sparc*|ppc|power*|parisc*|mips*) LIBOBJFLAGS='$(PIC)' ;;
         esac
     fi
 fi