Consistently pass through PKG_CONFIG_LIBDIR environment variable

src/platform/update_engine/SConstruct

 # Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Protobuffer compilation
 """ Inputs:
         target: list of targets to compile to
         source: list of sources to compile
         env: the scons environment in which we are compiling
     Outputs:
@@ skipping 49 matching lines @@
                        gthread-2.0
                        libpcrecpp
                        protobuf
                        pthread
                        ssl
                        xml2
                        z""")
 env['CPPPATH'] = ['..', '../../third_party/chrome/files', '../../common']
 env['LIBPATH'] = ['../../third_party/chrome']
 env['BUILDERS']['ProtocolBuffer'] = proto_builder
+
+# Fix up the pkg-config path if it is present in the environment.
+for key in Split('PKG_CONFIG_LIBDIR PKG_CONFIG_PATH'):
+  if os.environ.has_key(key):
+    env['ENV'][key] = os.environ[key]
+
 env.ParseConfig('pkg-config --cflags --libs glib-2.0')
 env.ProtocolBuffer('update_metadata.pb.cc', 'update_metadata.proto')
 
 if ARGUMENTS.get('debug', 0):
   env['CCFLAGS'] += ' -fprofile-arcs -ftest-coverage'
   env['LIBS'] += ['gcov']
 
 
 
 sources = Split("""action_processor.cc
@@ skipping 57 matching lines @@
                                  unittest_sources + test_installer_main)
 
 Clean(unittest_cmd, Glob('*.gcda') + Glob('*.gcno') + Glob('*.gcov') +
                     Split('html app.info'))
 
 delta_generator_cmd = env.Program('delta_generator',
                                   sources + delta_generator_sources +
                                   delta_generator_main)
 
 http_server_cmd = env.Program('test_http_server', 'test_http_server.cc')