ELF: Update comments.
ELF: Update comments.

This patch updates comments in the ELFLinkingContext to use
non-question sentences as brief descriptions of functions.

git-svn-id: f6089bf0e6284f307027cef4f64114ee9ebb0424@233774 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lld,llvm-mirror/lld