remove(?) mk6/mk5c dead wood descended from VGOS branch

[wehimwich]

There are several bits of dead wood out there related to mark6/5c from the VGOS branch. Basically they are starts on commands that have not been implemented, yet. (5c is now only supported from the main branch with jive5ab, not drs.) Perhaps they can be removed, or maybe some can be used for the intended mark6 commands eventually, or maybe it is better to start over.

Files that might be deleted (needs to be checked) include:

clib/mk5c_scan_check_ds.h
clib/mk6_disk_pos_util.c
clib/mk6_record_util.c
clib/mk6_scan_check_util.c
quikv/mk6_disk_pos.c
quikv/mk6_disk_pos_dis.c
quikv/mk6_record.c
quikv/mk6_record_dis.c
quikv/mk6_scan_check.c
quikv/mk6_scan_check_dis.c

Other files that need some corresponding clean-up:

clib/Makefile
control/fscmd.ctl
quikv/Makefile
quikv/quikv.c

and maybe also some clean-up for:

control/fserr.ctl