Use Q_SIGNALS/Q_EMIT instead of signals/emit in generated sources
Summary:
Avoid potential clashes on symbols/macros from other libraries
Allows to use the generated header in projects which have
DQT_NO_SIGNALS_SLOTS_KEYWORDS or DQT_NO_KEYWORDS set
Reviewers: vandenoever
Reviewed By: vandenoever
Differential Revision: https://phabricator.kde.org/D15545