kernel/selinux-testsuite: fix module_load check
    
    The "conmakehash" program is not shipped on recent Fedora kernels (and
    who knows where else). Switch to "unifdef", which seems to be everywhere
    (and always an ELF executable).
    
    Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>