[DebugInfo] Add test cases for FlagNonTrivial

Summary:
This is a test case to go with D44406 which added FlagNonTrivial to mark that a C++ record is non-trivial to support CodeView debug emission. 

While it looks like FlagTypePassByValue can imply triviality and FlagTypePassByReference can imply non-triviality that is not true. Some non-trivial cases use a combination of FlagNonTrivial and FlagTypePassByValue instead of FlagTypePassByReference. See the test cases and D44406 for discussion.

Reviewers: dblaikie, rnk, zturner

Reviewed By: dblaikie

Subscribers: jdoerfert, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59010

llvm-svn: 355890