Add patch to fix `make configure'.

The x11/kdelibs4 update from r436971 made the CMake code stricter, which was
making libkscreen fail in `make configure' where CMake used to just show a
warning:

CMake Error at tests/CMakeLists.txt:9 (add_test):

add_test given test name "testscreenconfig" which already exists in this
directory.

Call Stack (most recent call first):

tests/CMakeLists.txt:13 (KSCREEN_TESTS)