NEWS: Add info about bugs #316181 and #316696

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13662 a5019735-40e9-0310-863c-91ae7b9d1cf9
Remove autotools requirement as it is not specific to s390.
Minor wording changes.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13663 a5019735-40e9-0310-863c-91ae7b9d1cf9