[zlib] Add crc_folding.c feature config and use it in crc32.c

Add build config for zlib_x86_simd, and define CRC32_SIMD_SSE42_PCLMUL
within it. Change crc32.c to use it to guard the crc_folding code, not
the unrelated ADLER32_SIMD_SSSE3 guard.

Bug: 1072308
Change-Id: I7146cf8b83086e5f706ae0c3ad4c13caa2ec0b01
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2156233
Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: Chris Blume <cblume@chromium.org>
Reviewed-by: Adenilson Cavalcanti <cavalcantii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760909}