[NFC] [FileCheck] Reapply fix init of objects in unit tests

Summary:
Fix initialization style of objects allocated on the stack and member
objects in unit test to use the "Type Var(init list)" and
"Type Member{init list}" convention. The latter fixes the buildbot
breakage.

Reviewers: jhenderson, probinson, arichardson, grimar, jdenny

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68425

llvm-svn: 373755