Cherry-pick compiler-rt revision 318044 and 319180.

Cherry-pick compiler-rt revision 318044 and 319180.

    [PowerPC][tsan] Update tsan to handle changed memory layouts in newer kernels

    In more recent Linux kernels with 47 bit VMAs the layout of virtual memory
    for powerpc64 changed causing the thread sanitizer to not work properly. This
    patch adds support for 47 bit VMA kernels for powerpc64.

    Tested on several 4.x and 3.x kernel releases.

Regtested/bootstrapped on ppc64le-linux with kernel 4.14; applying to
trunk/8.3.

2018-08-01  Marek Polacek  <polacek@redhat.com>

	PR sanitizer/86759
	* tsan/tsan_platform.h: Cherry-pick compiler-rt revision 318044.
	* tsan/tsan_platform_linux.cc: Cherry-pick compiler-rt revision
	319180.

From-SVN: r263229