Expose the has_non_ascii() function

This function is useful outside of log-tree.c, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

pretty.c

@@ -86,6 +86,18 @@ int non_ascii(int ch)
 	return !isascii(ch) || ch == '\033';
 }
 
+int has_non_ascii(const char *s)
+{
+	int ch;
+	if (!s)
+		return 0;
+	while ((ch = *s++) != '\0') {
+		if (non_ascii(ch))
+			return 1;
+	}
+	return 0;
+}
+
 static int is_rfc2047_special(char ch)
 {
 	return (non_ascii(ch) || (ch == '=') || (ch == '?') || (ch == '_'));