fix github issue #447 - casting area-effect spell

at self when blind.  Spell targetting would let player pick
hero's own spot but casting would reject it when blind because
hero didn't sense any monster there.  The player wanted to cast
skilled fireball at self to cure being turned into slime but
wasn't allowed.  (Targetting an adjacent spot would work for
fireball, but is only feasible when telepathy reveals a monster
there.)

While testing the one-line fix, I noticed that the message line
(tty) showed stale data (autodescribe info for target spot) as
the fireball I cast (when not blind) bounced around the vicinity.
Normally that's cleared when a message is issued or the when the
next command is requested, but skilled fireball causes multiple
explosion animations before either of those situations.

doc/fixes37.0

@@ -1,4 +1,4 @@
-NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.431 $ $NHDT-Date: 1611182248 2021/01/20 22:37:28 $
+NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.434 $ $NHDT-Date: 1611522041 2021/01/24 21:00:41 $
 
 General Fixes and Modified Features
 -----------------------------------
@@ -370,6 +370,11 @@ for configuration using external compression on save files that applied a name
 	been manually uncompressed, mangling file name trying to remove suffix
 an empty lamp hit by fire reported "the oil lamp catches fire" (but at least
 	didn't light)
+spells that require a target spot rather than a direction (like skilled
+	fireball) would not let a blinded hero target his/her own spot, with
+	feedback stating hero failed to hold location sufficiently in mind;
+	when not blind, such spells left autodescribe feedback for target spot
+	in the message window while the spell was being performed
 
 
 Fixes to 3.7.0-x Problems that Were Exposed Via git Repository