COFF: add test for /INCLUDE directives specified in bitcode

Summary: MSVC allows linker options to be specified in source code. One of these is the /INCLUDE directive, which specifies that a symbol must be added to the symbol table, even if it otherwise wouldn't be. Existing tests cover the case where the linker is given an object file with an /INCLUDE directive, but we also need to cover the case where /INCLUDE is specified in a bitcode file (as would happen when using LTO). This new test covers that case.

Reviewers: pcc, ruiu

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D29096

llvm-svn: 293107