VM Resident Executables update:

VM Resident Executables update:

Kernel Part:

	* decrement the exec_res_id counter in exec_sys_unregister, otherwise
	  we will have an incorrect count of currently resident executables.

	* add a structure called 'xresident' which stores enough information
	  about resident executables, so that we can export it to userland
	  via sysctl; the structure resides in sys/resident.h.

	* add a sysctl node, called 'vm.resident' which enumerates though
	  exec_res_list, i.e., the queue which stores information about the
	  executables that are currently resident

	* move the exec_res_list queue initialization and a MALLOC_DEFINE
	  near the top of the file, right after the include files; and also
	  initialize the exec_res_id counter to '0'.

	NOTE! The 'vm.resident' sysctl node is only available to root!

Userland Part:

	* add a '-l' option to resident(8), so that it displays the list
	  of executables that are currently memory-resident.

	* update the program usage string so that it is in par with the
	  functionality offered by the program.

	* update the manual page.

Requested-by:   	many...
Discussed-with: 	Matthew Dillon <dillon@backplane.com>