Add procfs-non-linux.stderr.exp variants to EXTRA_DIST.

For bz#344936 procfs-non-linux.stderr.exp was renamed and split into
procfs-non-linux.stderr.exp-with-readlinkat and
procfs-non-linux.stderr.exp-without-readlinkat add both to EXTRA_DIST.
Fixes make post-regtest-checks.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15271 a5019735-40e9-0310-863c-91ae7b9d1cf9
1 file changed