Set squash uploads to false. This should make git cl upload work
properly from SwiftShader for those who prefer that over 'git push'
to a ref.

Bug: None
Change-Id: Ib80fdbd28c2a7a5808ab73ceec8ddb98f8962e0b
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/41708Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>