engine: a search just begun shows itself

Ctrl+E and Ctrl+H gave no sign until a key produced candidates; with
nothing pending the popup even went away.  An empty search now shows
☺ or 漢 in the popup, so the user knows the next keys are a query.

strans.c

@@ -192,6 +192,8 @@ snapshot(Drawcmd *dc)
 		impre(&im, &pre);
 	if(!(activecap & Cclientpreedit))
 		dc->pre = pre;
+	if(search.lang && pre.n == 0)	/* a search just begun shows itself */
+		sputr(&dc->pre, search.lang == LangEMOJI ? L'☺' : L'漢');
 	first = pagefirst();
 	n = im.nkouho - first;
 	if(n > Maxdisp) n = Maxdisp;