ARM: use ALT_BITSTREAM_READER on cores with fast unaligned access

Originally committed as revision 20911 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/get_bits.h

@@ -40,7 +40,7 @@
 #endif
 
 #if !defined(LIBMPEG2_BITSTREAM_READER) && !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER)
-#   if ARCH_ARM
+#   if ARCH_ARM && !HAVE_FAST_UNALIGNED
 #       define A32_BITSTREAM_READER
 #   else
 #       define ALT_BITSTREAM_READER