ARM: disable movw/movt for relocated values on Apple platforms

Apparently Apple platforms do not handle movw/movt relocations
properly, leading to runtime crashes in code using them.

Originally committed as revision 25150 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/arm/asm.S

@@ -62,7 +62,7 @@ ELF     .type   \name, %function
 .endm
 
 .macro  movrel rd, val
-#if HAVE_ARMV6T2 && !CONFIG_PIC
+#if HAVE_ARMV6T2 && !CONFIG_PIC && !defined(__APPLE__)
         movw            \rd, #:lower16:\val
         movt            \rd, #:upper16:\val
 #else