Remove kmtrace, kprofilemethod, kstartperf

As discussed on release-team@ mailing list (thanks dfaure), they
are obsolete, broken or both:
- kprofilemethod should to be replaced with something better/more
  convienent;
- kstartperf intercepts X11 calls, but Qt switched to XCB;
- kmtrace, which still needed to replace Q3Support and was not
  possible to reproduce its behavior, is definitely replaced by
  the heaptrack memory profiler.

See: https://mail.kde.org/pipermail/release-team/2017-February/010119.html