Change NOFORTH comment character from # to \ followed by space,

to make things more interchangeable between it and the FORTH case.

Perhaps requiring the space is a bit too much, but...

Nothing in the tree seems to produce loader.rc files with comment
line, at this time.

sys/boot/common/interp.c

@@ -219,7 +219,7 @@ include(const char *filename)
 #else
 	flags = 0;
 	/* Discard comments */
-	if (input[0] == '#')
+	if (strncmp(input+strspn(input, " "), "\\ ", 2) == 0)
 	    continue;
 	cp = input;
 	/* Echo? */