mie: func name and args are now specified separately from func creation

func args are added manually using mie_func_add_arg, while the func's name
is specified when the func is added to a module, to allow the module to generate
a unique name.

mie/arg.c

@@ -1,4 +1,22 @@
 #include <mie/arg.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct mie_arg *mie_arg_create(struct mie_type *type)
+{
+	struct mie_arg *out = malloc(sizeof *out);
+	if (!out) {
+		return NULL;
+	}
+
+	memset(out, 0x0, sizeof *out);
+
+	mie_value_init(&out->arg_base, MIE_VALUE_ARG);
+
+	out->arg_type = type;
+
+	return out;
+}
 
 static struct mie_type *get_type(struct mie_value *v)
 {