Summary:
* Update devel/qbs to 1.6.0
* Update devel/qtcreator to 4.1.0
* Add the QMAKE_LIBDIR_FLAGS hack we use in bsd.qt.mk for the Qt-ports.
This should hopefully make it possible to upgrade qbs & qtcreator
without deinstalling them first.
* As there is a qtcreator plugin linking against libqbscore.so, change
the RUN_- and BUILD_DEPENDS into a LIB_DEPENDS.
Test Plan: Tested in poudriere: 9.3 (32&64), 10.3 (32&64), 12 (64)
Reviewed by: rakuco
Approved by: rakuco (mentor)
Differential Revision: https://reviews.freebsd.org/D7884
7eac8c3d7a