Set GERRIT_SQUASH_UPLOADS to False.

ANGLE uses a workflow where we upload stacks of dependent patches to
Gerrit. The Chromium workflow has squashed by default for a long time,
so the infra team is planning to switch to squash by default. This
change will preserve our workflow.

See http://crbug.com/611892

BUG=None

Change-Id: I62ab7a26d5bd899fbb8c48a1aced7d044640a66a
Reviewed-on: https://chromium-review.googlesource.com/353039
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>

codereview.settings

@@ -2,3 +2,4 @@
 CODE_REVIEW_SERVER: https://chromium-review.googlesource.com
 GERRIT_HOST: True
 TRYSERVER_GERRIT_URL: https://chromium-review.googlesource.com
+GERRIT_SQUASH_UPLOADS: False