See 0d5e080ab9 for the previous version. Include
instructions on where to get the tools used.

807f96230c889b10f2957a47585426af4cdb116a8a77f1caecca83b7d7ab862b  cmake-3.5.0-win32-x86.zip
e6bb5c3e4d936bb1067560a58a21260693a0fbe34e55afb0111fe14f7eebc92c  strawberry-perl-5.22.1.2-32bit-portable.zip

Change-Id: I504cf779abce26087d09c0c974fb481886c9c459
Reviewed-on: https://boringssl-review.googlesource.com/7413
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

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>