use the A32_BITSTREAM_READER by default on ARM (faster)

Originally committed as revision 6120 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/bitstream.h

@@ -15,9 +15,13 @@
 //#define ALT_BITSTREAM_WRITER
 //#define ALIGNED_BITSTREAM_WRITER
 #if !defined(LIBMPEG2_BITSTREAM_READER) && !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER)
+#   ifdef ARCH_ARMV4L
+#       define A32_BITSTREAM_READER
+#   else
 #define ALT_BITSTREAM_READER
 //#define LIBMPEG2_BITSTREAM_READER
 //#define A32_BITSTREAM_READER
+#   endif
 #endif
 #define LIBMPEG2_BITSTREAM_READER_HACK //add BERO