Introduce sanstats tool and llvm::CreateSanitizerStatReport function.

This is part of a new statistics gathering feature for the sanitizers.
See clang/docs/SanitizerStats.rst for further info and docs.

Differential Revision: http://reviews.llvm.org/D16174

llvm-svn: 257970
GitOrigin-RevId: f0f5e870831fc4ac78c18f6fb786a9bea37e8aa9
10 files changed