tsan: implement malloc stats querying


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@173332 91177308-0d34-0410-b5e6-96231b3b80d8
[ASan] fix compilation on Mac by adding a missing pwrite parameter.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@173333 91177308-0d34-0410-b5e6-96231b3b80d8