Fix [#22099] Interactive Loopcut hs anoyin problem

Made the loop cut confirmation (when finding an edge ring to cut) happen on 
mouse press, rather than release.

This has a nice side effect when using the 'release confirm' option, combining 
the two steps into one - with this on you can click once to immediately place the 
cut in the center, or click+drag to move the cut line where you want it to.

See: http://mke3.net/blender/devel/2.5/loopcut_releaseconfirm.mov

source/blender/editors/mesh/loopcut.c

@@ -413,7 +413,7 @@ static int ringcut_modal (bContext *C, wmOperator *op, wmEvent *event)
 
 	switch (event->type) {
 		case LEFTMOUSE: /* confirm */ // XXX hardcoded
-			if (event->val == KM_RELEASE) {
+			if (event->val == KM_PRESS) {
 				/* finish */
 				ED_region_tag_redraw(lcd->ar);