GN: get Angle compiling on Windows.
Angle does not yet link, but it does compile.
I chickened out and wrote cp.py to be the copy tool on Windows. I've got all platforms using it for consistency.
CQ_INCLUDE_TRYBOTS=master.client.skia.compile:Build-Ubuntu-GCC-x86_64-Release-ANGLE-Trybot
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3533
Change-Id: I15f4b63a47121528b2fd2672c26c62765966147c
Reviewed-on: https://skia-review.googlesource.com/3533
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>