Add client requests
   VALGRIND_DISABLE_ADDR_ERROR_REPORTING_IN_RANGE and
   VALGRIND_ENABLE_ADDR_ERROR_REPORTING_IN_RANGE
and supporting machinery for managing whole-address-space sparse
mappings.  n-i-bz.  In support of
https://bugzilla.mozilla.org/show_bug.cgi?id=970643



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13884 a5019735-40e9-0310-863c-91ae7b9d1cf9