Un-nest configs in GN files.

third_party/usrsctp/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/crypto.gni")
 
 config("usrsctp_config") {
   include_dirs = [
     "usrsctplib",
     "usrsctplib/netinet",
   ]
 }
 
+config("usrsctp_warnings") {
+  if (is_clang) {
+    # atomic_init in user_atomic.h is a static function in a header.
+    cflags = [ "-Wno-unused-function" ]
+  }
+}
+
 static_library("usrsctp") {
   sources = [
     "usrsctplib/netinet/sctp.h",
     "usrsctplib/netinet/sctp_asconf.c",
     "usrsctplib/netinet/sctp_asconf.h",
     "usrsctplib/netinet/sctp_auth.c",
     "usrsctplib/netinet/sctp_auth.h",
     "usrsctplib/netinet/sctp_bsd_addr.c",
     "usrsctplib/netinet/sctp_bsd_addr.h",
     "usrsctplib/netinet/sctp_callout.c",
@@ skipping 53 matching lines @@
   ]
 
   defines = [
     "SCTP_PROCESS_LEVEL_LOCKS",
     "SCTP_SIMPLE_ALLOCATOR",
     "__Userspace__",
 
     # "SCTP_DEBUG", # Uncomment for SCTP debugging.
   ]
 
-  config("usrsctp_warnings") {
-    if (is_clang) {
-      # atomic_init in user_atomic.h is a static function in a header.
-      cflags = [ "-Wno-unused-function" ]
-    }
-  }
   configs -= [ "//build/config/compiler:chromium_code" ]
-  configs += [ "//build/config/compiler:no_chromium_code" ]
-  configs += [ "//build/config/compiler:no_incompatible_pointer_warnings" ]
-  configs += [ ":usrsctp_warnings" ]
+  configs += [
+    "//build/config/compiler:no_chromium_code",
+    "//build/config/compiler:no_incompatible_pointer_warnings",

[Nico, 2015/09/02 17:05:36]

(fwiw, this too must be after no_chromium_code. it happens to be after it in
lexicographic order, which i guess is why it doesn't have an explicit comment?)

+
+    # Must be after no_chromium_code for warning flags to be ordered correctly.
+    ":usrsctp_warnings",
+  ]
 
   public_configs = [ ":usrsctp_config" ]
 
   if (use_openssl) {
     defines += [ "SCTP_USE_OPENSSL_SHA1" ]
   } else {
     defines += [ "SCTP_USE_NSS_SHA1" ]
   }
 
   if (is_linux || is_android) {
@@ skipping 19 matching lines @@
     ]
     configs -= [ "//build/config/win:winver" ]
   } else {
     defines += [ "NON_WINDOWS_DEFINE" ]
   }
 
   deps = [
     "//crypto:platform",
   ]
 }