Re-land migrate md5sum tool to portable zlib utils

Use the set of portable code from zlib that shouldn't have
extra dependencies (e.g. 'base').

Also allow building the tool for other targets (e.g. Linux,
OSX, etc) as that allows easier testing and profiling.

Compilation is disabled for Windows, see crbug.com/1090428.

Bug: 1076580, 1087999
Change-Id: Ic036685029be99b06753ea18f9fc62ce7c1a6540
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2225526


Reviewed-by: Tao Bai <michaelbai@chromium.org>
Reviewed-by: Adenilson Cavalcanti <cavalcantii@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Adenilson Cavalcanti <cavalcantii@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#774325}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 00c7f91f09462399fff5e5266eeddcd6e0c9405c