QtAutogen: Extract a GetRccExecutable method.
QtAutogen: Expand rccfiles into a vector early in the autogen process.

This can be re-used as a vector.
QtAutogen: Regenerate qrc files if their input changes (#15074)

Get dependencies from the output of ``rcc --list`` if using
Qt 5. Otherwise process the file in the same way as the
qt4_add_resources macro.
Merge topic 'autorcc-depends' into next

034344ac QtAutogen: Regenerate qrc files if their input changes (#15074)
131ccd99 QtAutogen: Expand rccfiles into a vector early in the autogen process.
a4842771 QtAutogen: Extract a GetRccExecutable method.