Commit 3fa2d384 added a binary 'elf2dmp' but did not ignore it
during an in-tree build.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20190313144557.8845-1-eblake@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>