strings didn't recognize Runeerror something other than a utf character, in
contradiction of the man page (and utility.)

Reference: /n/sources/patch/applied/strings-valid-rune
Date: Fri Apr 28 23:26:59 CES 2006
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/strings.c	Fri Apr 28 23:25:21 2006
+++ /sys/src/cmd/strings.c	Fri Apr 28 23:25:18 2006
@@ -81,7 +81,7 @@
 int
 isprint(Rune r)
 {
-	if ((r >= ' ' && r <0x7f) || r > 0xA0)
+	if ((r >= ' ' && r <0x7f) || (r > 0xA0 && r < Runeerror))
 		return 1;
 	else
 		return 0;