Guard against buggy ucrt\math.h.

BUG=666707

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=5089

CQ_INCLUDE_TRYBOTS=master.client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Change-Id: I3bebfdf635d541d92fb84236f0f6fae2da39d691
Reviewed-on: https://skia-review.googlesource.com/5089
Reviewed-by: Bruce Dawson <brucedawson@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
8 files changed