fix "Killed by foo, while paralyzed by a monster"

If the killer and the paralyzer are the same monster, truncate
that to "Killed by a foo, while paralyzed".  When not the same,
spell out the paralyzer's monster type instead of using generic
"monster".  "Killed by a fox, while paralyzed by a ghoul", or
"Killed by a ghoul, while paralyzed by a ghoul" *if* they were
two different ghouls.

include/decl.h

@@ -717,6 +717,7 @@ struct instance_globals {
     char command_line[COLNO];
     long command_count;
     const char *multi_reason;
+    char multireasonbuf[QBUFSZ]; /* note: smaller than usual [BUFSZ] */
     int nroom;
     int nsubroom;
     int occtime;