Adding new configuration helpers

The configuration tests specific for the different languages belong to the different Waf tools representing the languages supported. For example, The configuration tests for the C language are located in the tool config_c.py. To enable this, decorators are used to attach new configuration tests dynamically, for example:

from Configure import conf

@conf
def get_define(self, define):
	"get the value of a previously stored define"
	try: return self.env[DEFINES][define]
	except KeyError: return None
			

Then the new configuration test may be used easily in wscript:

def configure(conf):
	print(conf.get_define('DEBUG'))