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/ctx.h

@@ -0,0 +1,18 @@
+#ifndef IFC_CTX_H_
+#define IFC_CTX_H_
+
+#include "type.h"
+
+struct ctx {
+	struct type ctx_builtin_types[TYPE_OTHER];
+};
+
+extern struct ctx *ctx_create(void);
+extern void ctx_destroy(struct ctx *ctx);
+
+extern const struct type *ctx_get_type(struct ctx *ctx, const char *name);
+extern const struct type *ctx_get_builtin_type(
+	struct ctx *ctx,
+	enum type_id id);
+
+#endif