Currently the added test produces false race reports with glibc 2.19,
because DLTS memory is reused by pthread under the hood.
Use the DTLS machinery to intercept new DTLS ranges.
__tls_get_addr known to cause issues for tsan in the past,
so write the interceptor more carefully.
Reviewed in http://reviews.llvm.org/D20927
llvm-svn: 271568
Dmitry Vyukov