Disable the forceOldRewriteStructSamplers feature for SwiftShader on
Android.  Another change fixed the issue that prevented SwiftShader on
Android from supporting sampler arrays as parameters.  The Qualcomm
driver still cannot support sampler arrays as parameters, and so it
still needs forceOldRewriteStructSamplers.

Bug: angleproject:4071
Bug: angleproject:2703
Change-Id: I77fbfacdad6cd9cc918c79fa0918f15de0558ce0
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2086282
Commit-Queue: Ian Elliott <ianelliott@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>