QtAutogen: Separate source file processing from AUTOMOC.

This will allow using AUTOUIC without using AUTOMOC for example.
QtAutogen: Short-circut some logic when moc is not available.

This is the case when AUTOMOC is false.  This prevents creating rules
to moc the files in the absense of moc.
Merge topic 'fix-Qt-autogen' into next

a7c73c48 QtAutogen: Short-circut some logic when moc is not available.
eaa25606 QtAutogen: Separate source file processing from AUTOMOC.