replace scm_c_primitive_load() with scm_primitive_load()

The c version does not auto-compile scripts, the other version
however does.

riverguile.c

@@ -310,8 +310,14 @@ static void *load_script (void *data)
 {
 	/* Note: All guile objects are garbage collected. */
 
-	char *path = (char *)data;
-	(void)scm_c_primitive_load(path);
+	const char *path = (char *)data;
+
+	/* scm_primitive_load_path() searches guiles load-path when encountering
+	 * a relative path. That should never happen here though.
+	 */
+	assert(path[0] == '/');
+
+	scm_primitive_load_path(scm_from_utf8_string(path));
 
 	/* Check if the handler has been defined. */
 	SCM variable = scm_module_variable(