Added generation of the llvm 'sret' parameter attribute where applicable. Fixed some wrong argument handling code when setting parameter attributes. Updated the tango unittest script in the tango patch, does not work yet, all modules don't compile...

enum
{
    LLVMnone,
    LLVMintrinsic,
    LLVMno_typeinfo,
    LLVMno_moduleinfo,
    LLVMalloca,
    LLVMva_start,
    LLVMva_copy,
    LLVMva_end,
    LLVMva_arg
};