This commit adds the 'kdiff3' package to the repo.
(*) Patched the generated makefile to use /usr instead of /usr/local.
PATCH 2: Fixed review comment and removed arm builds
(*) Clarified short description.
(*) Removed dead comments.
(*) Fixed maintainer and license to use SPDX expr.
(*) Removed arm builds since qmake is missing on those platforms.
PATCH 3: Fixed missing endquote in maintainer line
(*) Removed comments regarding license.
(*) Move qt tools to hostmakedepends to allow compile on arm/aarch64.
PATCH 4: Rework per review comment
(*) Fixed hostmakedepends and makedepends
(*) Converted to use qmake build_style per review comment
PATCH 5: Fix review comment
(*) Removed end of file newline.
(*) use ${SOURCEFORGE_SITE} instead of fixed URL.