NFC; clean up this file based on our coding standards. The impetus was considerable...

NFC; clean up this file based on our coding standards. The impetus was considerable use of a type name as an identifier for an object.

Changed identifier names (especially function parameters) to not clash with type names and to follow the proper naming conventions. Use of explicit type names changed to use auto where appropriate. Removed unused parameters that should have never been added in the first place. Minor formatting cleanups.

The changes were mostly mechanical and should have no functional impact.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@325256 91177308-0d34-0410-b5e6-96231b3b80d8