Convert third_party source sets to static libraries.

third_party/libXNVCtrl/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.
 
 # This warning disable must be appended to the command line after the general
 # warnings setup, so must be in a config.
 config("libXNVCtrl_config") {
   # This will build under most configurations with this warning enabled, but
   # some older system headers are missing a "const" on the third parameter of
   # XextAddDisplay which will cause a failure.
-  cflags = [
-    "-Wno-incompatible-pointer-types-discards-qualifiers",
-  ]
+  cflags = [ "-Wno-incompatible-pointer-types-discards-qualifiers" ]
 }
 
-source_set("libXNVCtrl") {
+static_library("libXNVCtrl") {
   sources = [
     "NVCtrl.c",
     "NVCtrl.h",
     "NVCtrlLib.h",
     "nv_control.h",
   ]
 
   configs += [
     ":libXNVCtrl_config",
     "//build/config/linux:x11",
   ]
 }