Make it possible for IBuildSystem to provide extra arguments to the parser

Authored by apol on Sep 9 2017, 11:05 PM.

Description

Make it possible for IBuildSystem to provide extra arguments to the parser

Summary:
So far it was limited to defines and includes, but there's more to life
than that.
This implements it for cmake where I tested it most, also for qmake where
I'm not sure how to yet it won't be worse than ignoring the variables.

Reviewers: KDevelop, kfunk

Subscribers: kdevelop-devel

Differential Revision: https://phabricator.kde.org/D7752