Fixed Bug Which Caused Infinite Loop While Highlighting Kconfig Files

Summary:
Fixed bug where typing menu or menuconfig while editng a kconfig file would cause the loop at abstracthighlighter.cpp:299 to get stuck in an infite loop. This would occur because the config_entry_start and menu_entry contexts would push an error line end context and the error line end context would pop back to the config_entry or menu_entry contexts.

There should probably also be a loop counter or something in that loop to keep
the end application from dying due to a bad definition.

Test Plan: Open up a kconfig file in a text editor and attempt to type "menu", "config", or "menuconfig"

Reviewers: Framework: Syntax Highlighting, cullmann, dhaumann

Reviewed By: Framework: Syntax Highlighting, cullmann

Subscribers: kde-frameworks-devel, nibags, kwrite-devel

Tags: Kate, Frameworks

Differential Revision: https://phabricator.kde.org/D18509