ig-c99: use idl-api 'idl_get_basetypes()'

lm-c99/ig-c99.ysl2

@@ -138,7 +138,7 @@ tstylesheet {
 
         // idl basetypes
         // -------------
-        ``apply "basetypes", 0
+        ``call "basetypes"
 
 
         #ifdef __cplusplus
@@ -147,8 +147,8 @@ tstylesheet {
         ||
     }
 
-    template "basetypes" {
-        for "*" {
+    function "basetypes" {
+        for "func:idl_get_basetypes()" {
             const "name", "name()";
             if "func:c99_typename_of_idltype($name) != $name" {
                 | «func:typedef(func:c99_typename_of_idltype($name), $name)»