Add MIPS to list of architectures requiring PIC flags.

Prior to gcc version 4.3 PIC was the default, now it needs to be enabled
explicitly. Passing the flag to older gcc versions does not hurt.

Originally committed as revision 15392 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1897,7 +1897,7 @@ if enabled shared; then
     # LIBOBJFLAGS may have already been set in the OS configuration
     if test -z "$LIBOBJFLAGS" ; then
         case "$arch" in
-            x86_64|ia64|alpha|sparc*|power*|parisc*) LIBOBJFLAGS='$(PIC)' ;;
+            x86_64|ia64|alpha|sparc*|power*|parisc*|mips*) LIBOBJFLAGS='$(PIC)' ;;
         esac
     fi
 fi