[clang-format] [NFC] clang-format the Format library

Previously revisions commited non-clang-formatted changes to the Format library, this means submitting any revision e.g. {D55170} can cause additional whitespace changes to potentially be included in a revision.

Commit a non functional change using latest build Windows clang-format r351376 with no other changes, to remove these differences

All FormatTests
pass [==========] 652 tests from 20 test cases ran.

llvm-svn: 355182