Pass capn_ptr by value, better handling of tags

compiler/capnpc-c.c

@@ -0,0 +1,29 @@
+#include "schema.h"
+
+
+int main() {
+	struct capn capn;
+	struct CodeGeneratorRequest_ptr root;
+	struct CodeGeneratorRequest req;
+	int i;
+
+	if (capn_init_fp(&capn, stdin)) {
+		fprintf(stderr, "failed to read schema on input\n");
+		return -1;
+	}
+
+	root.p = capn_root(&capn);
+	read_CodeGeneratorRequest(&root, &req);
+
+	for (i = 0; i < req.nodes.size; i++) {
+		struct Node_ptr p;
+		struct Node n;
+		p.p = capn_getp(&req.nodes, i);
+		read_Node(&p, &n);
+
+		fprintf(stderr, "node %s id:%#llx scope:%#llx type:%d\n",
+				n.displayName.str, n.id, n.scopeId, n.body_tag);
+	}
+
+	return 0;
+}