[clang-tidy] Changes to modernize-use-default check

Summary:
Warn about special member functions that only contain a comment.
Report the location of the special member function, unless it is
defined in a macro.  Reporting the location of the body in a macro is
more helpful as it causes the macro expansion location to be reported too.

Fixes PR30920.

Reviewers: alexfh, aaron.ballman

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D26741

llvm-svn: 287215