fix libdraw cf2subfont bug. depth var was equal to zero, and subfontname function was unable to locate subfont file. to reproduce the bug:

scat
moon
moon	....
plot
stringwidth: bad character set for rune 0x0000 in /lib/font/bit/lucida/unicode.6.font
...

Notes:
Sat Jan 22 11:17:42 EST 2005 rsc
    thanks for including easy-to-test
    demonstrations of the bug being fixed!
    
    russ
    


Reference: /n/sources/patch/applied/libdraw-cf2subfont
Date: Sat Jan 22 17:16:17 CET 2005
Reviewed-by: rsc

--- /sys/src/libdraw/font.c	Sat Jan 22 17:16:17 2005
+++ /sys/src/libdraw/font.c	Sat Jan 22 17:16:17 2005
@@ -154,11 +154,9 @@
 
 	name = cf->subfontname;
 	if(name == nil){
-		depth = 0;
-		if(f->display){
-			if(f->display->screenimage)
-				depth = f->display->screenimage->depth;
-		}else
+		if(f->display && f->display->screenimage)
+			depth = f->display->screenimage->depth;
+		else
 			depth = 8;
 		name = subfontname(cf->name, f->name, depth);
 		if(name == nil)