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.

src/decl.c

@@ -259,6 +259,9 @@ const struct instance_globals g_init = {
     UNDEFINED_VALUES, /* command_line */
     0, /* command_count */
     NULL, /* multi_reason */
+    /* multi_reason usually points to a string literal (when not Null)
+       but multireasonbuf[] is available for when it needs to be dynamic */
+    DUMMY, /* multireasonbuf[] */
     0, /* nroom */
     0, /* nsubroom */
     0, /* occtime */