Cherry-pick libsanitizer pointer-pair tristate option.

Cherry-pick libsanitizer pointer-pair tristate option.

2018-02-05  Martin Liska  <mliska@suse.cz>

	* doc/invoke.texi: Cherry-pick upstream r323995.
2018-02-05  Martin Liska  <mliska@suse.cz>

	* c-c++-common/asan/pointer-compare-1.c: Adjust ASAN_OPTIONS
	options.
	* c-c++-common/asan/pointer-compare-2.c: Likewise.
	* c-c++-common/asan/pointer-subtract-1.c: Likewise.
	* c-c++-common/asan/pointer-subtract-2.c: Likewise.
	* c-c++-common/asan/pointer-subtract-3.c: Likewise.
	* c-c++-common/asan/pointer-subtract-4.c: Likewise.
	* c-c++-common/asan/pointer-compare-3.c: New test.
2018-02-05  Martin Liska  <mliska@suse.cz>

	* asan/asan_flags.inc: Cherry-pick upstream r323995.
	* asan/asan_report.cc (CheckForInvalidPointerPair):
	Cherry-pick upstream r323995.

From-SVN: r257387