GN: Return array from pkgconfig wrapper

tools/gn/secondary/crypto/ssl/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.
 
 import("flags.gni")
 
 config("ssl_preprocessor_flags") {
   if (use_openssl) {
     defines = [ "USE_OPENSSL" ]
   } else if (use_nss) {
     defines = [ "USE_NSS" ]
   }
 }
 
 # Config for system SSL on Linux.
 if (is_linux && use_system_ssl) {
   pkg_script = "//build/config/linux/pkg-config.py"
   config("system_ssl_config") {
     defines = [ "USE_SYSTEM_SSL" ]
-    cflags = exec_script(pkg_script, [ "--cflags", "nss" ], "list lines")
-    ldflags = exec_script(pkg_script, [ "--libs", "nss" ], "list lines")
+    pkgresult = exec_script(pkg_script, [ "nss" ], "value")
+    includes = pkgresult[0]
+    cflags = pkgresult[1]
+    ldflags = pkgresult[2]
   }
 }
 
 # This meta-target will include the SSL library according to the build flags.
 group("metassl") {
   direct_dependent_configs = [ ":ssl_preprocessor_flags" ]
 
   if (use_openssl) {
     assert(is_linux)
     deps = "//third_party/openssl"
     use_openssl = false
   } else if (use_system_ssl) {
     assert(is_linux)
     direct_dependent_configs = ":system_ssl_config"
   } else {
     deps = [ "//net/third_party/nss/ssl" ]
   }
 
   forward_dependent_configs_from = deps
 }