win/clang: Remove -Wno-microsoft-enum-value.

The warning is no longer enabled by default in clang; no need to disable it.

BUG=505296

Review-Url: https://codereview.chromium.org/2954703002
Cr-Original-Commit-Position: refs/heads/master@{#482010}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: fbc74507346bb5e3ce3c0808d7d4e3e3edab1aa6
1 file changed