Update LTO plugin interface

[Ian Lance Taylor]

Cary Coutant <ccoutant@google.com> writes:

> My suggestion was to have the plugin give the linker a list of
> libcalls, and the linker would note where it found each symbol during
> its normal library scanning.

Ah, I see.  OK, that makes sense.

> Right. The gcc driver would have to have some concept of which
> libraries might contain libcalls, and add brackets around them on the
> linker command line to mark them as runtime support libraries, whether
> they're added by the driver itself, or passed on the gcc command line
> by the user.

Sounds good.

Ian