[tsan] Ensure mmap respects ignore_interceptors_accesses

The ignore_interceptors_accesses setting did not have an effect on mmap, so
let's change that. It helps in cases user code is accessing the memory
written to by mmap when the synchronization is ensured by the code that
does not get rebuilt.

(This effects Swift interoperability since it's runtime is mapping memory
which gets accessed by the code emitted into the Swift application by the
compiler.)

Differential Revision: http://reviews.llvm.org/D20294

llvm-svn: 269855