Disable variable shadow warnings on more ES1 conformance tests The list of gles1 sources is used in several targets without a common config. Bug: angleproject:6703 Change-Id: Ib78719c9dc322075dfba05380e99ec1ada8a3265 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3289616 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>