ECMAddQch: add INCLUDE_DIRS argument

Summary:
Allows to have headers be found by doxygen, e.g. to properly process
preprocessor macros.

Reviewers: Build System, dfaure

Reviewed By: dfaure

Subscribers: dfaure, kde-frameworks-devel, kde-buildsystem

Tags: Frameworks, Build System

Differential Revision: https://phabricator.kde.org/D23791