Revert of Revert of clang: Suppress a -Wstring-conversion warnings in nspr.

build/secondary/third_party/nss/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/linux/pkg_config.gni")
 
 if (is_linux) {
   # This is a dependency on NSS with no libssl. On Linux we use a built-in SSL
   # library but the system NSS libraries. Non-Linux platforms using NSS use the
   # hermetic one in //third_party/nss.
@@ skipping 314 matching lines @@
 
     if (is_clang) {
       cflags += [
         # nspr uses a bunch of deprecated functions (NSLinkModule etc) in
         # prlink.c on mac.
         "-Wno-deprecated-declarations",
         # nspr passes "const char*" through "void*".
         "-Wno-incompatible-pointer-types",
         # nspr passes "int*" through "unsigned int*".
         "-Wno-pointer-sign",
+      ]
 
-        "-Wno-incompatible-pointer-types",
-        "-Wno-pointer-sign",
-      ]
+      # nspr uses assert(!"foo") instead of assert(false && "foo").
+      configs -= [ "//build/config/clang:extra_warnings" ]
     }
   }
 
   component("nss") {
     output_name = "crnss"
     sources = [
       # Ensure at least one object file is produced, so that MSVC does not
       # warn when creating the static/shared library. See the note for
       # the "nssckbi" target for why the "nss" target was split as such.
       "nss/lib/nss/nssver.c",
@@ skipping 860 matching lines @@
       ":nspr",
       "//third_party/sqlite",
     ]
 
     if (is_win && cpu_arch == "x86") {
       deps += [ ":nss_static_avx" ]
     }
   }
 }  # Windows/Mac/iOS.