[PATCH] Always add LLVMgold.so plugin if it's present in the standard location

[Rafael Espíndola]

>> That is probably fine. Note that we always try to make llvm and clang
>> build options be just the default value of a runtime option. Not sure
>> if that would be strictly needed in here since the compile time option
>> would just be what -flto is during link time.
>
>
> Could we just detect whether the linker is gold in the driver?
>
> That would let us:
>
> 1) produce an error if using BFD ld and -flto
> 2) pass the plugin argument safely in all cases where it would be useful

Current versions of BFD support plugins. Gold (and BFD) can also be
compiled without plugin support, so the detection is not trivial. We
would also have to run the linker twice, no? Once to find if it
supports plugins and then again to actually link.

Cheers,
Rafael