Revert "Qt4: Fix moc command dependencies for incremental build."

This reverts commit ee9410a94e2a1a02b3183848bce9e48eb602c4bd.

This requires evaluation of the DEPENDS as generator expressions,
which is not yet possible.
Merge topic 'fix-Qt4-moc-command-depends' into next

1a2f178c Revert "Qt4: Fix moc command dependencies for incremental build."