Roll SwiftShader 680bcf5..a124f04

https://swiftshader.googlesource.com/SwiftShader.git/+log/680bcf5..a124f04

BUG=

TBR=kbr@chromium.org

TEST=bots

CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel,linux_chromium_cfi_rel_ng;master.tryserver.chromium.android:android_optional_gpu_tests_rel

Change-Id: I8dc42fe5c66471c75b51a2d4fadf1e9796bb125f
Reviewed-on: https://chromium-review.googlesource.com/955929
Commit-Queue: Alexis Hétu <sugoi@chromium.org>
Reviewed-by: Alexis Hétu <sugoi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543605}

DEPS

@@ -99,7 +99,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.
-  'swiftshader_revision': '680bcf50597a8a6939f9023a4c8ebed597f9c4ae',
+  'swiftshader_revision': 'a124f042c3b49cf1917a070ff66c8b333f9d48d7',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.