bit_reader.c: s/VP8L_USE_UNALIGNED_LOAD/VP8L_USE_FAST_LOAD/
bit_reader.c: s/VP8L_USE_UNALIGNED_LOAD/VP8L_USE_FAST_LOAD/

no longer gate this on WEBP_FORCE_ALIGNED as WebPMemToUint32() provides
this service. replace that check with WORDS_BIGENDIAN as the block is
currently little-endian specific.

Change-Id: Ie04ec0179022d20dab53da878008ae049837782f

webmproject/libwebp,PKRoma/libwebp,PKRoma/libwebp,webmproject/libwebp,webmproject/libwebp,webmproject/libwebp,PKRoma/libwebp,PKRoma/libwebp,PKRoma/libwebp,PKRoma/libwebp,webmproject/libwebp