This fixes a crash when a second pass is required for the Codeview Type...

This fixes a crash when a second pass is required for the Codeview Type merging *and* the index points outside of the table (which should lead to an error being printed).

This occurs currently until MS precompiled headers .obj is added (see D45213)

Differential Revision: https://reviews.llvm.org/D50006

llvm-svn: 338308