Revision 338902

In preparation for Qt 5 ports:

Mk/Uses/qmake.mk:
- Add support for out-of-source builds
- Add support for Qt 5 ports
- Respect WITH_DEBUG

Mk/bsd.qt.mk:
- Massive rework for Qt 5 ports
- Remove '-phonon' from global configure args, thus allow qt4-designer and
  qt4-qtconfig to be built without Phonon support [1]

devel/qmake4:
- Improve mkspecs for gcc (mainly sync with linux version) and clang

devel/qt4-corelib:
- Convert to USES=iconv
- Remove ancient patch

devel/qt4-designer:
- Remove reference to WRKSRC from installed pkgconfig files [2]
- Don't build Qt Designer plugin for Phonon from outdated Qt sources.
  Separate port for plugin will be committed later

devel/qt4-assistant-adp, devel/qt4-libqtassistantclient:
- Convert to USES=qmake

Clean up Qt4 ports:
- Update comments
- Update description; use common description
- Consistently use QT_INCDIR, QT_LIBDIR, etc.
- Use options helpers
- Convert to new LIB_DEPENDS syntax
- Update DESKTOP_ENTRIES to avoid conflicts with Qt 5 ports
- Rename/move several ports for unification with Qt 5 ports

PR:		ports/184620 [1]
Reported by:	Kevin Zheng <kevinz5000@gmail.com>

PR:		ports/181141 [2]
Reported by:	thierry

PR:		ports/185101
Exp-run by:	bdrewery

This is mostly solely avilla's work in area51, kudos to him! And a couple
commits from myself, so you know who's collecting pointyhats :)