Cut down unnecessary zero'ing when value-initializing arrays of C++ objects.

-C++ objects with user-declared constructor don't need zero'ing.
-We can zero-initialize arrays of C++ objects in "bulk" now, in which case don't zero-initialize each object again.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130453 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed