safe_oname (trunk only)

There were routines that were passed the
object name as an argument.  Before the oextra
patch, ONAME() always returned a valid pointer
to a location within the obj struct. The oextra
patch worked around those cases by
using a temporary variable that was either set
to ONAME (if the obj passed the has_oname() test),
or to ""  (pointer to an empty string) if no name was
present.

Since that might be a common thing to do, provide
the safe_oname() routine that you can use as a
function parameter without having to worry about
about whether ONAME(obj) is valid, and without
the need for the temporary variable.

include/extern.h

@@ -353,6 +353,7 @@ E void FDECL(new_mname, (struct monst *,int));
 E void FDECL(free_mname, (struct monst *));
 E void FDECL(new_oname, (struct obj *,int));
 E void FDECL(free_oname, (struct obj *));
+E const char *FDECL(safe_oname, (struct obj *));
 E struct monst *FDECL(christen_monst, (struct monst *,const char *));
 E int NDECL(do_mname);
 E struct obj *FDECL(oname, (struct obj *,const char *));