Use large enough buffers.


git-svn-id: svn://svn.valgrind.org/valgrind/branches/BUF_REMOVAL@14310 a5019735-40e9-0310-863c-91ae7b9d1cf9
Yet another spot where I missed to change the initialisation of the
directory name.


git-svn-id: svn://svn.valgrind.org/valgrind/branches/BUF_REMOVAL@14311 a5019735-40e9-0310-863c-91ae7b9d1cf9