Revert of Un-nest configs in GN files.

third_party/usrsctp/BUILD.gn

Index: third_party/usrsctp/BUILD.gn
diff --git a/third_party/usrsctp/BUILD.gn b/third_party/usrsctp/BUILD.gn
index 3accc19e29f128ba06e60cac4cde6c4d33ea20c0..bbea24b858fea7de37599c9a6345f7a2f7ea2763 100644
--- a/third_party/usrsctp/BUILD.gn
+++ b/third_party/usrsctp/BUILD.gn
@@ -9,13 +9,6 @@
     "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") {
@@ -91,12 +84,16 @@
     # "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 += [
-    ":usrsctp_warnings",
-    "//build/config/compiler:no_chromium_code",
-    "//build/config/compiler:no_incompatible_pointer_warnings",
-  ]
+  configs += [ "//build/config/compiler:no_chromium_code" ]
+  configs += [ "//build/config/compiler:no_incompatible_pointer_warnings" ]
+  configs += [ ":usrsctp_warnings" ]
 
   public_configs = [ ":usrsctp_config" ]