Simplify gnustep ports
Hook into the regular ports framework:
- LIB_DEPENDS for library dependencies
- Use regular USE_LDCONFIG
Reuse USES=objc (automatic)
USE_GNUSTEP is now a macro to set the dependencies and build feature needed.
Accepted arguments: back base build gui
Merge deskutils/preferencepanes into deskutils/systempreferences
06f79b66f2