This replaces bsd.qt.mk with qt.mk

Files are moved this way:

• svn mv Mk/bsd.qt.mk Mk/Uses/qt.mk
• svn rm Mk/Uses/qmake.mk

Changes for ports:

• USE_QT4=<list> becomes USE_QT=<list> with the additional USES=qt:4
• USE_QT5=<list> becomes USE_QT=<list> with the additional USES=qt:5
• USES=qmake has gone away and is replaced by USE_QT=qmake_build. The reasoning behind this is the following: qmake.mk and bsd.qt.mk where heavily intertwined. qmake.mk required $QT_VERSION which was chosen in bsd.qt.mk depending on whether USE_QT4 or USE_QT5 was set. The whole thing was somewhat circular. Now, given that most/allmost all? ports that used USES=qmake also set USE_QT[45]=qmake_build we can suck this handling into qt.mk and get rid of qmake.mk.
• For ports that had USES=qmake and already set USE_QT[45]=qmake_build the only change is to drop qmake from the USES, add qt:[45], and replace USE_QT[45]= by USE_QT=.
• Ports that did not yet qmake_build in their USE_QT[45] also need to add it.
• Arguments previously for qmake.mk now have to be passed to qt.mk with the prefix qmake_.
  • USES=qmake:outsource -> USES=qt:[45],qmake_outsource
  • USES=qmake:nonrecursive -> USES=qt:[45],qmake_nonrecursive
• There is also qmake_dummy which probably isn't needed ¯\_(ツ)_/¯ The idea of this is that ports that set USE_QT=qmake_build can opt out of having qmake at configure stage. The ports that would use qmake_dummy could also just set USE_QT=qmake instead of qmake_build. as qmake gets added as a BUILD_DEPENDS by default...

Issues

• I'm not quite sure about the way I set DESTDIRNAME.
• Same for the conditions to add qmake_configure to _USES_configure.

Non issues

• Seems to mostly work so far: From the Qt-using 1021 ports I tested I got 16 errors back -- and they seem unrelated to the changes.

• Finish a test build of everything that includes qt.mk.