libselinux: audit2why: remove unused module_state structure

This structure has been empty since its introduction and makes clang
complain when $(filter-out -Werror, $(CFLAGS)) is removed in the
Makefile target for audit2why.lo:

    audit2why.c:443:1: error: empty struct has size 0 in C, size 1 in
    C++ [-Werror,-Wc++-compat]
      struct module_state {
      ^
      1 error generated.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
1 file changed