GN: Return array from pkgconfig wrapper

tools/gn/secondary/build/config/linux/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.
 
 # Sets up the dynamic library search path to include our "lib" directory.
 config("executable_ldconfig") {
   ldflags = [
     # Want to pass "\$". Need to escape both '\' and '$'. GN will re-escape as
     # required for ninja.
     "-Wl,-rpath=\\\$ORIGIN/lib/",
 
     "-Wl,-rpath-link=lib/",
   ]
 }
 
+# This script returns a list consisting of two nested lists: the first is the
+# list of cflags, the second are the linker flags.
 pkg_script = "pkg-config.py"
 
 config("fontconfig") {
   ldflags = [ "-lfontconfig" ]
 }
 
 config("freetype2") {
-  cflags = exec_script(pkg_script, [ "--cflags", "freetype2" ], "list lines")
-  ldflags = exec_script(pkg_script, [ "--libs", "freetype2" ], "list lines")
+  pkgresult = exec_script(pkg_script, [ "freetype2" ], "value")
+  cflags = pkgresult[0]
+  ldflags = pkgresult[1]
 }
 
 config("glib") {
-  glib_packages = "glib-2.0 gmodule-2.0 gobject-2.0 gthread-2.0"
-
-  cflags = exec_script(pkg_script, [ "--cflags", glib_packages ], "list lines")
-  ldflags = exec_script(pkg_script, [ "--libs", glib_packages ], "list lines")
+  pkgresult = exec_script(pkg_script,
+    [ "glib-2.0", "gmodule-2.0", "gobject-2.0", "gthread-2.0" ], "value" )
+  cflags = pkgresult[0]
+  ldflags = pkgresult[1]
 }
 
 config("gtk") {
   # Gtk requires gmodule, but it does not list it as a dependency in some
   # misconfigured systems.
-  gtk_packages = "gmodule-2.0 gtk+-2.0 gthread-2.0"
+  pkgresult = exec_script(pkg_script,
+    [ "gmodule-2.0", "gtk+-2.0", "gthread-2.0" ], "value" )
+  cflags = pkgresult[0]
+  ldflags = pkgresult[1]
 
   defines = [ "TOOLKIT_GTK" ]
-
-  cflags = exec_script(pkg_script, [ "--cflags", gtk_packages ], "list lines")
-  ldflags = exec_script(pkg_script, [ "--libs", gtk_packages ], "list lines")
 }
 
 config("pangocairo") {
-  cflags = exec_script(pkg_script, [ "--cflags", "pangocairo" ], "list lines")
-  ldflags = exec_script(pkg_script, [ "--libs", "pangocairo" ], "list lines")
+  pkgresult = exec_script(pkg_script, [ "pangocairo" ], "value" )
+  cflags = pkgresult[0]
+  ldflags = pkgresult[1]
 }
 
 config("udev") {
-  udev_packages = "libudev"
-
-  cflags = exec_script(pkg_script, [ "--cflags", udev_packages ], "list lines")
-  ldflags = exec_script(pkg_script, [ "--libs", udev_packages ], "list lines")
+  pkgresult = exec_script(pkg_script, [ "libudev" ], "value" )
+  cflags = pkgresult[0]
+  ldflags = pkgresult[1]
 }
 
 config("x11") {
   # Don't bother running pkg-config for these X related libraries since it just
   # returns the same libs, and forking pkg-config is slow.
   defines = [ "USE_X11" ]
   ldflags = [
     "-lX11",
     "-lXcomposite",
     "-lXcursor",
     "-lXdamage",
     "-lXext",
     "-lXfixes",
     "-lXi",
     "-lXrender",
     "-lXss",
     "-lXtst",
   ]
 }