Enable EliminateAvailableExternally pass for -O1

Summary:
Follow-up to D43690, the EliminateAvailableExternally pass currently
runs under -O0 and -O2 and up. Under -O1 we would still want to drop
available_externally symbols to reduce space without inlining having
run.

Reviewers: tejohnson

Reviewed By: tejohnson

Subscribers: mehdi_amini, llvm-commits, kcc

Differential Revision: https://reviews.llvm.org/D46093

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330961 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed