Simplify FsUtilTest.cpp
Simplify FsUtilTest.cpp

Summary:
This test suite used to wrap equality of two paths by using `EXPECT_TRUE` to
avoid an old bug in GTest 1.6.0. Now that we use GTest 1.8.0, we can
simplify our test.
Closes https://github.com/facebook/folly/pull/780

Differential Revision: D7052503

Pulled By: yfeldblum

fbshipit-source-id: 5459736fca04cc45acf88a3d7dffc855ad7c9376

facebook/folly,rklabs/folly,rklabs/folly,rklabs/folly,facebook/folly,facebook/folly,rklabs/folly,facebook/folly,facebook/folly,rklabs/folly