makes vncv send scroll button events to the other side (it only sent 3 bits worth previously)

Reference: /n/sources/patch/applied/vncv-scroll
Date: Tue Dec  7 15:25:40 CET 2004

--- /sys/src/cmd/vnc/wsys.c	Tue Dec  7 15:25:40 2004
+++ /sys/src/cmd/vnc/wsys.c	Tue Dec  7 15:25:40 2004
@@ -145,7 +145,7 @@
 			if(*start == 'm'){
 				m.xy.x = atoi(start+1);
 				m.xy.y = atoi(start+1+12);
-				m.buttons = atoi(start+1+2*12) & 7;
+				m.buttons = atoi(start+1+2*12) & 0x1F;
 				m.xy = subpt(m.xy, screen->r.min);
 				if(ptinrect(m.xy, Rpt(ZP, v->dim)))
 					mouseevent(v, m);