meta-pkgs/kde4/kde4.mk was discussed. The conclusion was that it did
make sense to include that definition because kde4.mk is included by
packages that use the kde4 configure and build system, which is cmake.
Thus, they will need to define USE_CMAKE anyway and currently must do
so in addition to including kde4.mk. This adds the needed definition
so that it is no longer necessary to do both things.
Many other packages currently include kde4.mk and also define USE_CMAKE.
In many cases they also define CMAKE_ARGS. To avoid potential confusion
centering around wondering whether or not USE_CMAKE was forgotten (e.g.,
if readers do not know it is now defined in kde4.mk), the definition was
not removed from those packages.
Future package authors can determine whether or not it is clearer to
include the definition even though kde4.mk is also included.
[1] http://mail-index.netbsd.org/tech-pkg/2011/08/28/msg007595.html
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