9term, win: work around bsd linker nonsense

Change-Id: Ifcef0636ee1e1fd0f9b06a8d1a99d58fae831318
Reviewed-on: https://plan9port-review.googlesource.com/2780
Reviewed-by: Russ Cox <rsc@swtch.com>

include/draw.h

@@ -525,6 +525,8 @@ extern	int	_drawdebug;	/* set to 1 to see errors from flushimage */
 extern	void	_setdrawop(Display*, Drawop);
 extern	Display	*_initdisplay(void(*)(Display*,char*), char*);
 
+extern	void	needdisplay(void); /* call instead of initdraw to get (null) variable linked in */
+
 #define	BGSHORT(p)		(((p)[0]<<0) | ((p)[1]<<8))
 #define	BGLONG(p)		((BGSHORT(p)<<0) | (BGSHORT(p+2)<<16))
 #define	BPSHORT(p, v)		((p)[0]=(v), (p)[1]=((v)>>8))

src/cmd/9term/bsdpty.c

@@ -77,10 +77,10 @@ updatewinsize(int row, int col, int dx, int dy)
 	ws.ws_col = col;
 	ws.ws_xpixel = dx;
 
-
+	needdisplay(); // in case this is 'win' and not 9term
 	// Leave "is this a hidpi display" in the low bit of the ypixel height for mc.
 	dy &= ~1;
-	if(display->dpi >= DefaultDPI*3/2)
+	if(display != nil && display->dpi >= DefaultDPI*3/2)
 		dy |= 1;
 	ws.ws_ypixel = dy;
 

src/libdraw/init.c

@@ -19,6 +19,11 @@ Image	*mousebuttons;
 Image	*mousesave;
 Mouse	_drawmouse;
 
+void
+needdisplay(void)
+{
+}
+
 /*
 static void
 drawshutdown(void)