Revert "Fix missed exception spec checks and crashes"

The changes caused the sanitizer bot to hang:
  http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/2311

Needs investigation.

This reverts commit r192914.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@192921 91177308-0d34-0410-b5e6-96231b3b80d8
[ms-cxxabi] Error out on virtual function memptrs

These are uncommon and this is better than miscompiling.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@192923 91177308-0d34-0410-b5e6-96231b3b80d8