Fix wildcard matching for modelines

Summary:
This patch adds a unit test for reading kate modelines.
In particular, the unit test ensures that the following examples work correctly:

1. kate: variable value;
2. kate-wildcard(*.txt): variable value;
3. kate-wildchard(*.foo;*.txt;*.bar): variable value;
4. kate-modeline(text/plain): variable value;
5. kate-modeline(text/foo;text/plain;text/bar): variable value;

The unit test found that 3. did not work correctly due to a wrong
bool assignment. This is now fixed.

Test Plan: make test

Reviewers: cullmann, kfunk, mwolff, nalvarez, brauch

Reviewed By: brauch

Subscribers: brauch, Frameworks

Tags: Kate, Frameworks

Differential Revision: https://phabricator.kde.org/D9569