Bug 1767612 - Update to sixgill that optimizes out trivial loops

Differential Revision: https://phabricator.services.mozilla.com/D146257

taskcluster/scripts/misc/build-gcc-sixgill-plugin-linux.sh

@@ -11,7 +11,7 @@ root_dir=$MOZ_FETCHES_DIR
 build_dir=$GECKO_PATH/build
 data_dir=$GECKO_PATH/build/unix/build-gcc
 
-sixgill_rev=dee1cfae08c2
+sixgill_rev=9b7f4a7bf67a
 sixgill_repo=https://hg.mozilla.org/users/sfink_mozilla.com/sixgill
 
 . $data_dir/build-gcc.sh