Convert GN single-item list concat to use lists.

tools/gn/secondary/third_party/libusb/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("libusb_config") {
   include_dirs = [
     "src/libusb",
   ]
 }
 
@@ skipping 30 matching lines @@
     "src/libusb/version.h",
     "src/libusb/version_nano.h",
     "src/msvc/config.h",
     "src/msvc/inttypes.h",
     "src/msvc/stdint.h",
   ]
   include_dirs = [
     "src/libusb/os",
   ]
 
-  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 = [ ":libusb_config" ]
 
   if (is_posix) {
     defines = [
       "DEFAULT_VISIBILITY=",
       "HAVE_GETTIMEOFDAY=1",
       "HAVE_POLL_H=1",
       "HAVE_SYS_TIME_H=1",
       "LIBUSB_DESCRIBE=\"1.0.16\"",
       "POLL_NFDS_TYPE=nfds_t",
       "THREADS_POSIX=1",
     ]
   }
 
   if (is_mac) {
-    defines += "OS_DARWIN=1"
+    defines += [ "OS_DARWIN=1" ]
   } else {
     sources -= [
       "src/libusb/os/darwin_usb.c",
       "src/libusb/os/darwin_usb.h",
     ]
   }
 
   if (is_linux || is_android) {
     defines += [
       "HAVE_LIBUDEV=1",
       "OS_LINUX=1",
       "USE_UDEV=1",
       "_GNU_SOURCE=1",
     ]
-    configs += "//build/config/linux:udev"
+    configs += [ "//build/config/linux:udev" ]
   } else {
     sources -= [
       "src/libusb/os/linux_udev.c",
       "src/libusb/os/linux_usbfs.c",
       "src/libusb/os/linux_usbfs.h",
     ]
   }
 
   if (is_win) {
-    include_dirs += "src/msvc"
+    include_dirs += [ "src/msvc" ]
   } else {
-    include_dirs += "src"
+    include_dirs += [ "src" ]
     sources -= [
       "src/libusb/os/poll_windows.c",
       "src/libusb/os/poll_windows.h",
       "src/libusb/os/threads_windows.c",
       "src/libusb/os/threads_windows.h",
       "src/libusb/os/windows_common.h",
       "src/libusb/os/windows_usb.c",
       "src/libusb/os/windows_usb.h",
       "src/msvc/config.h",
       "src/msvc/inttypes.h",
       "src/msvc/stdint.h",
     ]
   }
 }