Return false status only when adding a route is failed.  It could
erroneously return false due to an afexists() check loop in routing_start().


git-svn-id: svn+ssh://svn.freebsd.org/base/head@270783 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
vt(4): Change vb_history_size from "int" to "unsigned int"

CID:		1230002, 1230003
MFC after:	1 week


git-svn-id: svn+ssh://svn.freebsd.org/base/head@270785 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
vt(4): Indicate that KDSETRAD case falls through the next case

CID:		1229953
MFC after:	1 week


git-svn-id: svn+ssh://svn.freebsd.org/base/head@270786 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f