lib/lzo: add unlikely hints to overrun checks

The NEED_* macros do an implicit goto in case the safety bounds checks
fail. Add the unlikely hints as this is the error case and not a hot
path. The final assembly is slightly shorter and some jumps got
reordered according to the hints.

   text    data     bss     dec     hex filename
   2294      16       0    2310     906 pre/lzo1x_decompress_safe.o
   2277      16       0    2293     8f5 post/lzo1x_decompress_safe.o

   text    data     bss     dec     hex filename
   3444      48       0    3492     da4 pre/lzo1x_compress_safe.o
   3372      48       0    3420     d5c post/lzo1x_compress_safe.o

Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>