[llvm] r274148 - Don't verify inputs to the Linker if ODR merging.

[Rafael Espíndola via llvm-commits]

> Does this mean the final Module will never be verified?

The final module can still be verified.

> In r268965, I added support for dropping invalid debug info (as caught by the verifier) in LTO to allow us to make the Verifier stricter in the future while still being able to compile bitcode produced by older versions of clang and I'm worried that this might break now.

This change was only to llvm-link, but what I think was already broken
is that using the verifier as LTO does can delete valid IR. When the
IR is first read with ODR type merging the types are already linked
and the verifier will think the debug info is broken.

Cheers,
Rafael