Consistently pass through PKG_CONFIG_LIBDIR environment variable

src/platform/window_manager/SConstruct

Index: src/platform/window_manager/SConstruct
diff --git a/src/platform/window_manager/SConstruct b/src/platform/window_manager/SConstruct
index 4e3b153c53bba3e523ae406129e48386ef5f315b..55320572c2ef86673606c1df8db435bd5159112f 100644
--- a/src/platform/window_manager/SConstruct
+++ b/src/platform/window_manager/SConstruct
@@ -55,8 +55,9 @@ if not base_env.get('CCFLAGS'):
 base_env['LINKFLAGS'] = '-lgflags -lprotobuf'
 
 # Fix up the pkg-config path if it is present in the environment.
-if os.environ.has_key('PKG_CONFIG_PATH'):
-  base_env['ENV']['PKG_CONFIG_PATH'] = os.environ['PKG_CONFIG_PATH']
+for key in Split('PKG_CONFIG_LIBDIR PKG_CONFIG_PATH'):
+  if os.environ.has_key(key):
+    env['ENV'][key] = os.environ[key]
 
 # Unless we disable strict aliasing, we get warnings about some of the
 # program's command line flags processing code that look like: