Merge branch 'tr/xdiff-fast-hash'

Use word-at-a-time comparison to find end of line or NUL (end of buffer), borrowed from the linux-kernel discussion. By Thomas Rast * tr/xdiff-fast-hash: xdiff: choose XDL_FAST_HASH code on sizeof(long) instead of __WORDSIZE xdiff: load full words in the inner loop of xdl_hash_record