Re-XFAIL UBSan vptr testcase on darwin.
Re-XFAIL UBSan vptr testcase on darwin.

Partial revert of r235961; the test still fails on Green Dragon bots.


git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@236135 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt