Suppress new Clang warning -Wbitwise-conditional-parentheses

Bug: 1016947
Change-Id: I5e5f36f5d0e727e35a7d8375cf47eefbfe47eec1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1879927
Auto-Submit: Hans Wennborg <hans@chromium.org>
Reviewed-by: Reid Kleckner <rnk@chromium.org>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709207}

build/config/compiler/BUILD.gn

@@ -1535,6 +1535,12 @@ config("default_warnings") {
           # TODO(https://crbug.com/995993): Clean up and enable.
           "-Wno-implicit-fallthrough",
         ]
+        if (llvm_force_head_revision) {
+          cflags += [
+            # TODO(https://crbug.com/1016947) Clean up, enable.
+            "-Wno-bitwise-conditional-parentheses",
+          ]
+        }
       }
     }
   }