[lldb-mi] Remove unwanted comment blocks.

Summary:
This removes Authors:, Gotchas:, Changes: and Copyright:.

It leaves a couple of Gotcha: blocks that were not empty.

Reviewers: abidh, ki.stfu, domipheus

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D11452

llvm-svn: 242996