MFC r311160, r311210, r311288, r311292, r311298, r311340

MFC r311160, r311210, r311288, r311292, r311298, r311340

r311160:
misc minor fixes in mpr(4)

sys/dev/mpr/mpr_sas.c
	* Fix a potential null pointer dereference (CID 1305731)
	* Check for overrun of the ccb_scsiio.cdb_io.cdb_bytes buffer (CID
	  1211934)

sys/dev/mpr/mpr_sas_lsi.c
	* Nullify a dangling pointer in mprsas_get_sata_identify
	* Fix a memory leak in mprsas_SSU_to_SATA_devices (CID 1211935)

Reported by:	Coverity (partially)
CID:		1305731 1211934 1211935
Reviewed by:	slm
MFC after:	4 weeks
Sponsored by:	Spectra Logic Corp
Differential Revision:	https://reviews.freebsd.org/D8880

r311210:
Quell Coverity for diskinfo(8)

* CID 1198994: Don't run the speed disk on a disk with no sectors
* CID 1011442: Don't call close(2) if open(2) fails
* CID 1011161: Use snprintf instead of sprintf
* CID 1009825: Check the return value of lseek

Reported by:	Coverity
CID:		1198994 1011442 1011161 1009825
MFC after:	4 weeks
Sponsored by:	Spectra Logic Corp

r311288:
Delete dead code in chat(8)

It's always been dead, ever since first import in 1994.  It's still dead in
OpenBSD's version, too.

Reported by:	Coverity
CID:		270586
MFC after:	4 weeks
Sponsored by:	Spectra Logic Corp

r311292:
Remove dead code in rpc_parse.c

It's been dead ever since it was imported from TI-RPC in 1995.  The dead
code is still present in Illumos today, but was removed from NetBSD in 2006.

Reported by:	Coverity
CID:		270097
Obtained from:	NetBSD
MFC after:	4 weeks
Sponsored by:	Spectra Logic Corp

r311298:
Remove dead code in dhclient(8)

The offending code has been dead ever since the import from OpenBSD in
r195805.  OpenBSD later deleted that entire function.

Reported by:	Coverity
CID:		500059
MFC after:	4 weeks
Sponsored by:	Spectra Logic Corp

r311340:
Misc Coverity fixes for tail(1)

CID 1006402:	Initialize stack variable
CID 271580:	Don't leak memory when ENOMEM.

Reported by:	Coverity
CID:		271580 1006402
MFC after:	4 weeks
Sponsored by:	Spectra Logic Corp