Pull up following revision(s) (requested by kamil in ticket #895):

usr.sbin/sysinst/util.c: revision 1.9

Fix invalid free(3) in sysinst(8)

The path variable is assigned with an allocation on the heap with
strdup(3). Later this pointer is changed with strsep(3) and this caused
invalid free(3).

Store the original pointer in a new helper variable opath and pass it to
free(3). With this change, the problem is going away.

Detected with MKSANITIZER=yes with AddressSanitizer.

(martin)