[UBSan] Various improvements to vptr.cpp test case

* Remove __ubsan_default_options, so that test would work on Darwin
* Fix unintentional undefined behavior in the code (missing return)
* Build the test with -fno-sanitize-recover to distinguish expected
  failures and expected passes by return code.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@236152 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed