Merging r359606:

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r359606 | amyk | 2019-04-30 13:09:00 -0700 (Tue, 30 Apr 2019) | 12 lines

[compiler-rt][builtins][sanitizers] Update compiler-rt test cases for
compatibility with system's toolchain

This patch aims to:
- Guard ompiler-rt/test/builtins/Unit/compiler_rt_logb_test.c with macros, so
the test runs on GLIBC versions >= 2.23. This is because the test relies on
comparing its computed values to libm. Oolder versions might not compute to the
same value as the compiler-rt value.
- Update compiler-rt/test/sanitizer_common/TestCases/Posix/getpw_getgr.cc
so that std::string is not used, since false positives may be detected.

Differential Revision: https://reviews.llvm.org/D60644
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llvm-svn: 362024