[clang-tidy] misc-use-after-move: Fix failing assertion

Summary:
I've added a test case that (without the fix) triggers the assertion,
which happens when a move happens in an implicitly called conversion
operator.

Reviewers: alexfh

Reviewed By: alexfh

Subscribers: JDevlieghere, cfe-commits

Differential Revision: https://reviews.llvm.org/D30569

llvm-svn: 297004