Merging r278357:

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r278357 | compnerd | 2016-08-11 09:58:12 -0700 (Thu, 11 Aug 2016) | 6 lines

test: relax the FS test a slight bit to be more reliable

Some filesystems track atime always.  This relaxes the test to accept either a
filesystem which does not accurately track atime or does track the atime
accurately.  This allows the test to pass on filesystems mounted with
`strictatime` on Linux or on macOS.
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llvm-svn: 278538