Patch to build libprotobuf-mutator on Windows landed upstream: https://github.com/google/libprotobuf-mutator/pull/99

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/94ba7cffc603e7d338ef05d5daa891dbfabff53a

commit 94ba7cffc603e7d338ef05d5daa891dbfabff53a
Author: Jonathan Metzman <metzman@chromium.org>
Date: Thu Sep 27 01:31:38 2018

Roll src/third_party/libprotobuf-mutator/src/ 3fc43a01d..c148984c5 (20 commits)

https://chromium.googlesource.com/external/github.com/google/libprotobuf-mutator.git/+log/3fc43a01d721..c148984c5af6

$ git log 3fc43a01d..c148984c5 --date=short --no-merges --format='%ad %ae %s'
2018-09-26 metzman change int32_t to uint32_t
2018-09-17 metzman remove whitespace change
2018-09-17 metzman [NFC] Change types for in uniform_int_distribution for Windows
2018-08-23 allenwebb Added "make install" and pkg-config file.
2018-09-07 35739080+Allen-Webb Added per field mutator hooks. (#98)
2018-09-04 vitalybuka Update .travis.yml
2018-08-24 vitalybuka Update libxml2.cmake
2018-08-23 vitalybuka Temporarily fix for libxml2 build issue
2018-08-23 vitalybuka Switch to https://gitlab.gnome.org/GNOME/libxml2
2018-06-25 vitalybuka Update README.md
2018-06-25 eneyman Edit links in README to reflect new file names.
2018-05-30 eneyman Add include statement to fix build
2018-03-06 vitalybuka Disable libFuzzer len_control.
2018-01-30 vitalybuka Update .travis.yml
2018-01-23 vitalybuka Update .travis.yml
2018-01-15 vitalybuka Disable gcc debug because gcc crashes there
2018-01-15 vitalybuka gcc 7
2018-01-15 vitalybuka nproc
2018-01-15 vitalybuka Fix -Werror=sign-compare
2018-01-15 vitalybuka Update protobuf Disabled leak sanitizer on travis, looks like travis removed SYS_PTRACE.

Created with:
  roll-dep src/third_party/libprotobuf-mutator/src

Bug:  884560 
Change-Id: I6861a5010af72bbd0c4305c0c68d7a7626b7bb6d
Reviewed-on: https://chromium-review.googlesource.com/1247323
Reviewed-by: Vitaly Buka <vitalybuka@google.com>
Commit-Queue: Jonathan Metzman <metzman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594554}
[modify] https://crrev.com/94ba7cffc603e7d338ef05d5daa891dbfabff53a/DEPS

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/342d2451ca39dade57f834dd747792a333e23c96

commit 342d2451ca39dade57f834dd747792a333e23c96
Author: Jonathan Metzman <metzman@chromium.org>
Date: Thu Sep 27 14:12:16 2018

[LPM][libFuzzer][Windows]Enable building libprotobuf-mutator on Windows

Bug:  884560 
Change-Id: I7e6ac6869b2e2e068214cc5944d73a22549e5a70
Reviewed-on: https://chromium-review.googlesource.com/1247189
Reviewed-by: Max Moroz <mmoroz@chromium.org>
Commit-Queue: Jonathan Metzman <metzman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594710}
[modify] https://crrev.com/342d2451ca39dade57f834dd747792a333e23c96/third_party/libprotobuf-mutator/BUILD.gn

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/91445a3f9a552be46638c93c0a855f57e018a89e

commit 91445a3f9a552be46638c93c0a855f57e018a89e
Author: Jonathan Metzman <metzman@chromium.org>
Date: Mon Nov 19 22:23:04 2018

[libFuzzer][Windows] Make fuzzable_proto_library work

Get fuzzable_proto_library working on Windows (and probably Mac) by including
a dummy source in our protobuf_full wrapper.
This causes the library to actually get built.

Bug:  884560 , 889889
Change-Id: I4c6a1f8b284448dfdf2845cf3fd9adfd6a4fcb78
Reviewed-on: https://chromium-review.googlesource.com/c/1343243
Reviewed-by: Max Moroz <mmoroz@chromium.org>
Commit-Queue: Jonathan Metzman <metzman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609466}
[modify] https://crrev.com/91445a3f9a552be46638c93c0a855f57e018a89e/testing/libfuzzer/libprotobuf-mutator.md
[modify] https://crrev.com/91445a3f9a552be46638c93c0a855f57e018a89e/third_party/libprotobuf-mutator/BUILD.gn
[add] https://crrev.com/91445a3f9a552be46638c93c0a855f57e018a89e/third_party/libprotobuf-mutator/dummy.cc
[modify] https://crrev.com/91445a3f9a552be46638c93c0a855f57e018a89e/third_party/libprotobuf-mutator/fuzzable_proto_library.gni

This should be working now.