QtAutogen: Add source files to target when only AUTORCC is used.

Add missing entry to if condition.
QtAutogen: Process all ui files in a source file (#14981).

Use a vector to store a list of matched ui_ includes, instead of
overwriting the previous match.
Merge topic 'autogen-fixes' into next

7bddcf33 QtAutogen: Process all ui files in a source file (#14981).
b8877b1d QtAutogen: Add source files to target when only AUTORCC is used.