[clang-tidy] misc-move-const-arg: Detect if result of std::move() is being...

[clang-tidy] misc-move-const-arg: Detect if result of std::move() is being passed as a const ref argument

Summary:
Conceptually, this is very close to the existing functionality of misc-move-const-arg, which is why I'm adding it here and not creating a new check. For example, for a type A that is both movable and copyable, this

  const A a1;
  A a2(std::move(a1));

is not only a case where a const argument is being passed to std::move(), but the result of std::move() is also being passed as a const reference (due to overload resolution).

The new check typically triggers (exclusively) in cases where people think they're dealing with a movable type, but in fact the type is not movable.

Reviewers: hokein, aaron.ballman, alexfh

Subscribers: aaron.ballman, cfe-commits

Patch by Martin Boehme!

Differential Revision: http://reviews.llvm.org/D21223

llvm-svn: 272896