Remove /dev/mem, /dev/kmem, /dev/port support.

	Remove /dev/mem, /dev/kmem, /dev/port support.
	* Makefile.in (DLL_OFILES): Drop fhandler_mem.o.
	(fhandler_mem_CFLAGS): Remove rule.
	* devices.in (enum fh_devices): Remove FH_MEM, FH_KMEM and FH_PORT.
	* devices.cc: Regenerate.
	* dtable.cc (fh_alloc): Drop handling for FH_MEM, FH_KMEM and FH_PORT.
	* fhandler.h (class fhandler_dev_mem): Remove.
	* fhandler_mem.cc: Remove file.
	* globals.cc (ro_u_pmem): Remove.
	* mmap.cc (fhandler_dev_mem::mmap): Remove.
	(fhandler_dev_mem::munmap): Remove.
	(fhandler_dev_mem::fixup_mmap_after_fork): Remove.