Update zlib to fix build errors in latest Clang.

The GN file has been updated to more closely match Chromium's, so
there are some reordering/whitespace changes that make the diff
more intimidating than strictly necessary.

Bug: chromium:1519899
Change-Id: Ibbd2d222d751a9bdb394ddf70666784cf21728ba
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/808219
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
4 files changed