Revert "[asan] Poor man's coverage that works with ASan"

This reverts commit 194701. Apple's bootstrapped LTO builds have been failing,
and this change (along with compiler-rt 194702-194704) is the only thing on
the blamelist.  I will either reappy these changes or help debug the problem,
depending on whether this fixes the buildbots.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194780 91177308-0d34-0410-b5e6-96231b3b80d8