These are upstream's prebuilt binaries of:
e9493171de  cmake-3.1.3-win32-x86.zip
ab6e7aee6a  strawberry-perl-5.20.2.1-32bit-portable.zip
4c4d195118  yasm-1.2.0-win32.exe

This is intentionally using yasm 1.2.0 rather than the latest 1.3.0 to match
Chromium's current bundled version. Chromium has additional patches, but they
all seem to be either in 1.2.0 or not relevant for us.

Also update extract.py a little to account for these.

BUG=430237

Change-Id: Iad6687e493900b25390d99882c7ceea62fff8b9b
Reviewed-on: https://boringssl-review.googlesource.com/3710
Reviewed-by: Adam Langley <agl@google.com>