[lto] Don't lazy load metadata for now.

Summary:
At the very least we hit

    Assertion failed: (((Flags & RF_HaveUnmaterializedMetadata) || Node->isResolved()) && "Unexpected unresolved node"), function MapMetadataImpl, file /Users/Sean/pg/llvm/lib/Transforms/Utils/ValueMapper.cpp, line 375.

on the included test case.

We currently do things like parse the module twice to keep the
implementation minimal. I think it makes sense to add start with eager
loading for similar reasons.

Reviewers: rafael

Subscribers: ruiu, Bigcheese, llvm-commits, joker.eph

Differential Revision: http://reviews.llvm.org/D17982

llvm-svn: 263045