build: Embed setting of PKG_CONFIG_PATH variable to commonly used values

Change-Id: Ib6a46b64bff07c3aa3e799a7490b45ba22fa4c5d
diff --git a/wscript b/wscript
index 45d2a32..cc94ade 100644
--- a/wscript
+++ b/wscript
@@ -22,6 +22,10 @@
 
     conf.env['ENABLE_NDNSIM']=False
 
+    if not os.environ.has_key('PKG_CONFIG_PATH'):
+        os.environ['PKG_CONFIG_PATH'] = ':'.join([
+            '/usr/local/lib/pkgconfig',
+            '/opt/local/lib/pkgconfig'])
     conf.check_cfg(package='libndn-cxx', args=['--cflags', '--libs'],
                    uselib_store='NDN_CXX', mandatory=True)