clang-format: Force line break between "endl" and "<<".

This makes piped output easier to read in many instances.

Before:
  llvm::errs() << aaaa << std::endl << bbbb << std::endl;

After:
  llvm::errs() << aaaa << std::endl
               << bbbb << std::endl;

Also fix a few instance of "don't use else after return" as per the
coding standards.

llvm-svn: 225444