Suppress -Wstring-concatenation

Bug: 1114873
Change-Id: I42175ba9b236541bb91ea732d731c10ae60fe458
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2349920
Commit-Queue: Arthur Eubanks <aeubanks@google.com>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797035}

build/config/compiler/BUILD.gn

@@ -1550,6 +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" ]
+        }
       }
     }
   }