[zlib] Add OS_FUCHSIA feature detection and enable zlib NEON crc32

Add OS_FUCHSIA ARM CPU feature detection and enable the crc32 feature
on the ARM version of Fuchsia (which is aarch64 only, FTR). For perf,
see the results crbug.com/810125/#c17 .. crbug.com/810125/#c19.

Add BUILD.gn asserts in the ARM crc32 feature rules: to vet any build
expectations (e.g., that the android NDK is installed on is_android),
or cause gn errors if the ARM OS type is not supported.

Bug: 810125
Change-Id: Id6759d4c6142924c09c591b61117dca529955175
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1472990


Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: Adenilson Cavalcanti <cavalcantii@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#650712}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: c96f4c5c7a0cdaf823373c4bb417978b8321ffb2