Fix a behavioral change accidentally introduced by the move to the LLVM commandline system: `-output-(bc|ll|s)` used to disable generation of an object file unless explicitly requested with `-output-o`. Now they do so again.

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