Compiling zdtm on the latest Fedora rawhide gives errors like this:

ns.c: In function ‘prepare_mntns’:
ns.c:122:13: error: In the GNU C Library, "makedev" is defined
 by <sys/sysmacros.h>. For historical compatibility, it is
 currently defined by <sys/types.h> as well, but we plan to
 remove this soon. To use "makedev", include <sys/sysmacros.h>
 directly. If you did not intend to use a system-defined macro
 "makedev", you should undefine it after including <sys/types.h>. [-Werror]
   if (mknod("/dev/ptmx", 0666 | S_IFCHR, makedev(5, 2)) == 0) {
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

This commit fixes those errors.

travis-ci: success for zdtm: fix '"makedev" is defined by <sys/sysmacros.h>'
Signed-off-by: Adrian Reber <areber@redhat.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>