[ELF] Clean up doxygen comments.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@173740 91177308-0d34-0410-b5e6-96231b3b80d8
[ELF] Remove OwningPtr from the Chunk::write interface.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@173741 91177308-0d34-0410-b5e6-96231b3b80d8