Convert GN single-item list concat to use lists.

tools/gn/secondary/third_party/zlib/BUILD.gn

 # Copyright (c) 2013 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.
 
 config("zlib_config") {
   include_dirs = [ "." ]
 }
 
 static_library("zlib") {
   external = true
@@ skipping 26 matching lines @@
     "mozzconf.h",
     "trees.c",
     "trees.h",
     "uncompr.c",
     "zconf.h",
     "zlib.h",
     "zutil.c",
     "zutil.h",
   ]
 
-  configs -= "//build/config/compiler:chromium_code"
-  configs += "//build/config/compiler:no_chromium_code"
+  configs -= [ "//build/config/compiler:chromium_code" ]
+  configs += [ "//build/config/compiler:no_chromium_code" ]
 
   direct_dependent_configs = [ ":zlib_config" ]
 }
 
 static_library("minizip") {
   external = true
   sources = [
     "contrib/minizip/ioapi.c",
     "contrib/minizip/ioapi.h",
     "contrib/minizip/iowin32.c",
@@ skipping 15 matching lines @@
     defines = [ "USE_FILE32API" ]
   }
 
   if (is_clang) {
     # zlib uses `if ((a == b))` for some reason.
     cflags = [ "-Wno-parentheses-equality" ]
   }
 
   deps = [ ":zlib" ]
 
-  configs -= "//build/config/compiler:chromium_code"
-  configs += "//build/config/compiler:no_chromium_code"
+  configs -= [ "//build/config/compiler:chromium_code" ]
+  configs += [ "//build/config/compiler:no_chromium_code" ]
   direct_dependent_configs = [ ":zlib_config" ]
 }
 
 static_library("zip") {
   external = true
   sources = [
     "google/zip.cc",
     "google/zip.h",
     "google/zip_internal.cc",
     "google/zip_internal.h",
     "google/zip_reader.cc",
     "google/zip_reader.h",
   ]
   deps = [
     ":minizip",
     "//base",
   ]
 }