wcc: delete unused warning counters and ww err twin

selfhost/cmd/wcc/check.ww

@@ -40,8 +40,7 @@ type checker = struct {
 // diagnostics. Tool-local (NOT a lib wrapper): messages are built from
 // many fragments and we route through os.write to avoid libc stdio.
 // .len replaces the error-prone hand-counted byte literals these sites
-// carried. Lives here (not err.ww) because the selfhost build pulls
-// check.ww but not err.ww (which ports err.c for the C-driven path).
+// carried.
 fn cerr(m: str) void = {
 	os.write(2, m.ptr, m.len: u64);
 };