fix #H8330 - kicking obj stack uses wrong weight

Kicking a stack splits off one item (except for gold coins) and
propels it, but the range for how far it would move was calculated
before the split using the entire stack's weight.  So a large stack of
small items might fail with "thump" (which the report suggested hurt
the hero, but it doesn't) and none of the stack would move.  Splitting
sooner looked complicated because of several potential early returns
between the range calculation and the eventual kick, so this hacks the
stack's quantity to get the intended weight instead.

doc/fixes36.2

@@ -1,4 +1,4 @@
-$NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.269 $ $NHDT-Date: 1551739190 2019/03/04 22:39:50 $
+$NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.270 $ $NHDT-Date: 1551920371 2019/03/07 00:59:31 $
 
 This fixes36.2 file is here to capture information about updates in the 3.6.x
 lineage following the release of 3.6.1 in April 2018. Please note, however,
@@ -389,6 +389,9 @@ wand or spell of undead turning handled messages and wand-discovery in a
 	non-intuitive manner biased toward healers
 if steed ate a mimic corpse and began masquerading as something, hero could
 	keep riding it; force dismount
+kicking an object stack moves the topmost 1, but range calculation used the
+	weight of the whole stack to decide how far it would move, possibly
+	yielding "thump" result with no movement despite being a light item
 
 
 Fixes to Post-3.6.1 Problems that Were Exposed Via git Repository