Can I define an RPm macro that takes a flag that may or may not have an argument?
Aka the behavior should be:
-> no flag used, assuming user doesn't want the X feature.
-> -X flag used without a value, assuming user wants the X feature, with defaults.
%macro -X foo
-> -X flag used with a value, assuming user wants the X feature, but want's to
use "foo instead of the default value for X.