SCons: Pass env to modules can_build method

This allows to disable modules based on the environment,
in particular `env[tools]` which tells us if we are
building the editor or not.

modules/regex/config.py

@@ -1,4 +1,4 @@
-def can_build(platform):
+def can_build(env, platform):
     return True
 
 def configure(env):