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.

llvm-svn: 194780