toolchain: add a program for compiling ipc interface definitions

ifc can be used to compile .if files into self-contained header-only C
libraries, which can be used to send/receive messages that conform
to the described interface.

toolchain/ifc/interface.h

@@ -0,0 +1,24 @@
+#ifndef IFC_INTERFACE_H_
+#define IFC_INTERFACE_H_
+
+#include <blue/core/queue.h>
+
+struct msg_definition;
+
+struct interface_definition {
+	char *if_name;
+	b_queue if_msg;
+};
+
+extern struct interface_definition *interface_definition_create(
+	const char *name);
+extern void interface_definition_destroy(struct interface_definition *iface);
+
+extern bool interface_definition_has_msg(
+	const struct interface_definition *iface,
+	const char *name);
+extern void interface_definition_add_msg(
+	struct interface_definition *iface,
+	struct msg_definition *msg);
+
+#endif