clang-cl: Expose the -Xclang option

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188685 91177308-0d34-0410-b5e6-96231b3b80d8
Simplify assert-neutral matching in test case.

Originally committed in r188651, improved/fixed to be assert-neutral by
Takumi in r188661.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188686 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "Revert "Revert "DebugInfo: Omit debug info for dynamic classes in TUs that do not have the vtable for that class"""

This reverts commit r188642.

This change is causing LTO builds to cause our 16 GB machines to swap and OOM
all weekend. I am going to work with Dave Blaikie to resolve the issue.

Sorry Dave =(.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188687 91177308-0d34-0410-b5e6-96231b3b80d8