Try to appease a buildbot.

The failure is:
C:\ps4-buildslave2\llvm-clang-x86_64-expensive-checks-win\llvm\unittests\ProfileData\CoverageMappingTest.cpp(244):
error C2668: 'llvm::make_unique': ambiguous call to overloaded function

http://lab.llvm.org:8011/builders/llvm-clang-x86_64-expensive-checks-win/builds/3489/

llvm-svn: 306784