Enable Windows host compilation of gflags am: 791196a1e8 am: 1e32a9e8c7 am: 073396cf0a am: c7e4441964 am: 16616fd81f

Original change: https://android-review.googlesource.com/c/platform/external/gflags/+/2411455

Change-Id: I41437d16511c72befd8686c73087b3520f8c0ac4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>