Update libpng to 1.6.37

Bug: 953747

- remove patches/0000-plte.patch, which has been integrated into
  upstream
- update README.chromium to remove references to the patch
- reapply 0001-chunkerror.patch and 0002-fuzzeroom.patch
- apply https://github.com/glennrp/libpng/pull/285 for ARM64
  clang-cl build

Change-Id: I0aa5e552b09309da4e65dbd0b9d6be5327b329e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1570916
Commit-Queue: Leon Scroggins <scroggo@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652124}
36 files changed