Comment only changes.
* Clarify in the dedup pool comments that all bytes of elements are compared.
* pub_core_options.h : remove old/misplaced comment for clo_trace_children
                       and replace by a more clear comment (matching the --help)


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14704 a5019735-40e9-0310-863c-91ae7b9d1cf9