build: Tweak default pkg-config search paths

Change-Id: Ife54d34b06795df2f58979d9197ea537646cc762
Refs: #2711
diff --git a/wscript b/wscript
index 4de9d08..d056296 100644
--- a/wscript
+++ b/wscript
@@ -25,6 +25,8 @@
     if not os.environ.has_key('PKG_CONFIG_PATH'):
         os.environ['PKG_CONFIG_PATH'] = ':'.join([
             '/usr/local/lib/pkgconfig',
+            '/usr/local/lib64/pkgconfig',
+            '/usr/local/lib32/pkgconfig',
             '/opt/local/lib/pkgconfig'])
     conf.check_cfg(package='libndn-cxx', args=['--cflags', '--libs'],
                    uselib_store='NDN_CXX', mandatory=True)