Improve address description for address in the stack.
--read-var-info=yes is very memory and cpu intensive.
This patch ensures that even witout --read-var-info=yes that
the frame where the address point is reported in the address
description.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13991 a5019735-40e9-0310-863c-91ae7b9d1cf9