fix #H4179 - death reason for rotted globs

'Poisoned by a rotted gray ooze corpse' should have been
'Poisoned by a rotted glob of gray ooze'.

eatcorpse() is called for non-corpse globs and then corpse_xname()
is called for them too to set up death reason for make_sick(), but
it didn't know anything about globs.  Now it does.  Blob size is
ignored since it's not relevant for cause of death.

doc/fixes36.1

@@ -88,6 +88,7 @@ make mimics mimicing walls or trees also block light
 stepping onto lava destroyed non-fireproof water walking boots but left other
 	vulnerable boot types intact
 allow moving cursor to monsters with 'm' and 'M' when asked for map location
+fix death reason when eating tainted glob of <monster> (not corpse)
 
 
 Platform- and/or Interface-Specific Fixes