Do not use -mdynamic-no-pic if PIC is enabled

Originally committed as revision 20145 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1901,7 +1901,7 @@ case $target_os in
         FFSERVERLDFLAGS=-Wl,-bind_at_load
         objformat="macho"
         enabled x86_64 && objformat="macho64"
-        enabled shared ||
+        enabled_any pic shared ||
             { check_cflags -mdynamic-no-pic && add_asflags -mdynamic-no-pic; }
         ;;
     mingw32*)