o Replace occurrences of strncpy(3) with strlcpy(3); most of

o Replace occurrences of strncpy(3) with strlcpy(3); most of
  the uses of it were wrong anyway.
o Always check for NULL returns on strdup(3).
o Fix a possible buffer overflow in strcpy(3).
o Fix a format string vulnerability.
o t->ty_type in stypeof() could be NULL and eventually cause
  a segmentation fault in setenv(3), so check for that.

Eyeballed by:	kris
Reviewed by:	murray
MFC after:	3 days