Delay creating an alias for @@@.

With this we only create an alias for @@@ once we know if it should
use @ or @@. This avoids last minutes renames and hacks to handle MS
names.

This only handles the ELF writer. LTO still has issues with @@@
aliases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@327160 91177308-0d34-0410-b5e6-96231b3b80d8
10 files changed