Revert "Roll clang llvmorg-12-init-1771-g1bd7046e-5 : llvmorg-12-init-3132-g95fad44e-1."

This reverts commit 0e1132cc.

Reason for revert: Probably broke the Windows deterministic builder, see https://ci.chromium.org/p/chromium/builders/ci/Windows%20deterministic/17001 for first failure

Original change's description:
> Roll clang llvmorg-12-init-1771-g1bd7046e-5 : llvmorg-12-init-3132-g95fad44e-1.
>
> Ran `./tools/clang/scripts/upload_revision.py 95fad44e34c3c20263961a715571d798d90921f6`.
>
> Bug: 1113154
> Change-Id: I2cbd4533fcedea8acfb6d5f5067e56c7d758d25b
> Cq-Include-Trybots: chromium/try:mac_chromium_asan_rel_ng
> Cq-Include-Trybots: chromium/try:linux_chromium_cfi_rel_ng
> Cq-Include-Trybots: chromium/try:linux_chromium_chromeos_asan_rel_ng
> Cq-Include-Trybots: chromium/try:linux_chromium_msan_rel_ng
> Cq-Include-Trybots: chromium/try:linux_chromium_chromeos_msan_rel_ng
> Cq-Include-Trybots: chromium/try:linux-chromeos-dbg,win-asan
> Cq-Include-Trybots: chromium/try:chromeos-amd64-generic-cfi-thin-lto-rel
> Cq-Include-Trybots: chromium/try:linux_chromium_compile_dbg_32_ng
> Cq-Include-Trybots: chromium/try:win7-rel,win-angle-deqp-rel-32
> Cq-Include-Trybots: chromium/try:linux_angle_deqp_rel_ng
> Cq-Include-Trybots: chromium/try:win-angle-deqp-rel-64
> Cq-Include-Trybots: chromium/try:dawn-win10-x86-deps-rel
> Cq-Include-Trybots: chrome/try:iphone-device,ipad-device
> Cq-Include-Trybots: chrome/try:linux-chromeos-chrome
> Cq-Include-Trybots: chrome/try:win-chrome,win64-chrome,mac-chrome
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2357413
> Commit-Queue: Nico Weber <thakis@chromium.org>
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#798480}

TBR=thakis@chromium.org,hans@chromium.org,aeubanks@google.com

Change-Id: Ifdc8d2aefe7c8750c9b11c97d17de59c363140df
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1113154
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2358934
Commit-Queue: Fergus Dall <sidereal@google.com>
Reviewed-by: Fergus Dall <sidereal@google.com>
Cr-Commit-Position: refs/heads/master@{#798506}

build/config/compiler/BUILD.gn

@@ -1537,9 +1537,6 @@ config("default_warnings") {
 
           # TODO(https://crbug.com/1050281): Clean up, enable.
           "-Wno-non-c-typedef-for-linkage",
-
-          # TODO(https://crbug.com/1114873): Clean up and enable.
-          "-Wno-string-concatenation",
         ]
 
         cflags_c += [
@@ -1553,6 +1550,12 @@ config("default_warnings") {
           # TODO(https://crbug.com/1049569): Remove after Clang 87b235db.
           cflags += [ "-Wno-max-tokens" ]
         }
+
+        if (llvm_force_head_revision) {
+          # TODO(https://crbug.com/1114873):
+          # Remove after false positives are fixed
+          cflags += [ "-Wno-string-concatenation" ]
+        }
       }
     }
   }

tools/clang/scripts/update.py

@@ -38,8 +38,8 @@ import zipfile
 # https://chromium.googlesource.com/chromium/src/+/master/docs/updating_clang.md
 # Reverting problematic clang rolls is safe, though.
 # This is the output of `git describe` and is usable as a commit-ish.
-CLANG_REVISION = 'llvmorg-12-init-3132-g95fad44e'
-CLANG_SUB_REVISION = 1
+CLANG_REVISION = 'llvmorg-12-init-1771-g1bd7046e'
+CLANG_SUB_REVISION = 5
 
 PACKAGE_VERSION = '%s-%s' % (CLANG_REVISION, CLANG_SUB_REVISION)
 RELEASE_VERSION = '12.0.0'