Update KDE Plasma to 5.12.7.

Bump PORTREVISION for ports depending on the canonical version of GCC
in the ports tree (via Mk/bsd.default-versions.mk and lang/gcc) which
has now moved from GCC 6 to GCC 7 by default.

This includes ports
 - featuring USE_GCC=yes or USE_GCC=any,
 - featuring USES=fortran,
 - using Mk/bsd.octave.mk which in turn features USES=fortran, and those
 - with USES=compiler specifying one of openmp, nestedfct, c11, c++0x,
   c++11-lib, c++11-lang, c++14-lang, c++17-lang, or gcc-c++11-lib.

PR:		222542

Replace bsd.qt.mk by Uses/qt.mk and Uses/qt-dist.mk

From now on, ports that depend on Qt4 will have to set
	USES=		qt:4
	USE_QT=		foo bar
ports depending on Qt5 will use
	USES=		qt:5
	USE_QT=		foo bar

PR:		229225
Exp-run by:	antoine
Reviewed by:	mat
Approved by:	portmgr (antoine)
Differential Revision:	-https://reviews.freebsd.org/D15540

Update KDE Plasma Desktop to 5.12.5

Submitted by:	lwhsu

Import the KDE Plasma5 ports

This is an import of the Plasma5 ports that we have had in the development
repository for quite some time now.

Please note:
 * Plasma5 cannot be installed at the same time as KDE SC4.
 * Qt5 assumes /etc/localtime to be a symlink to a tz file, not a regular file.
 * To start plasma5, it is recommended to use something like
       exec ck-launch-session startkde
 * Powermanagement and such is not working :-)

I would like to thank all the people that have helped test it in the past years.

Reviewed by:	adridg
Differential Revision:	https://reviews.freebsd.org/D15096