[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.

This patch also fixes nondeterministic behavior in the source code
location reported for the move when the move is constained in an init list;
this was causing buildbot failures in the previous attempt to submit
this patch (see D30569 and rL297004).

Reviewers: alexfh

Reviewed By: alexfh

Subscribers: Eugene.Zelenko, JDevlieghere, cfe-commits

Differential Revision: https://reviews.llvm.org/D30650

llvm-svn: 297272