wcc: mangle private decls as <module>.<name> via // MODULE: marker

selfhost/cmd/wcc/ast.ww

@@ -108,10 +108,11 @@ type node = struct {
 	exported: i32,	// bool — `export` keyword present
 	type_:   *void,	// filled in by checker; type.ww treats it as *tinfo
 	tsuffix: str,	// typed numeric literal suffix ("i32", "u64", ...)
+	module:  str,	// originating module from `// MODULE: foo`; "" if none
 };
 
 export fn newnode(a: *arena, k: i32, file: str, line: i32, col: i32) *node = {
-	let n: *node = amalloc(a, 192u64): *node;	// 192 ≥ struct size
+	let n: *node = amalloc(a, 208u64): *node;	// ≥ struct size
 	n.kind = k;
 	n.file = file;
 	n.line = line;