PATCH: Redesign GOT offset support in gold

["Cary Coutant" <ccoutant at google dot com>]

The attached patch is a redesign of the way gold stores GOT offsets
for local and global symbols. It's a bit cleaner (I think), and it
provides the foundation for supporting more than one or two kinds of
GOT entries for any symbol. In the new design, the local and global
symbol tables can store arbitrary types of GOT entries for each
symbol, and the GOT entry types are platform-specific. I did optimize
the implementation for the common case of at-most-one GOT entry per
symbol, though.

This redesign was necessary to support the TLS_DESC-style TLS model
from Alexandre Oliva, which I'm working on.

OK to commit?

-cary

Attachment: got-patch.txt
Description: Text document