graphics/darktable: update to new release 3.0.0
Announcement:
https://www.darktable.org/2019/12/darktable-300-released/
https://www.darktable.org/2019/12/darktable-30/
Additional changes:
- ONLY_FOR_ARCHS* variables moved up to please portlint
- some CMAKE_ARGS hacks with CMAKE_*_COMPILER_LAUNCHER to get ccache back in
- switch from hardcoding LLVM_VER=60 to ${LLVM_DEFAULT}
- strip out -D_XOPEN_SOURCE=... (upstream CMakeLists.txt) because it is harmful in hiding, for instance, u_char typedefs, which causes compilation failure down the road for cups_print.
PR: 242943
Approved by: dumbbell@ (maintainer)