fix !ENABLE_FEATURE_GETOPT_LONG build. Closes 3775

When compiling with !ENABLE_FEATURE_GETOPT_LONG, busybox still tries
to include getopt.h which is not available; for example with uClibc
when !UCLIBC_HAS_GETOPT_LONG.  getopt.h is only required
for the _long set of functions.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

selinux/runcon.c

@@ -50,7 +50,6 @@
 //usage:     "\n	-l RNG	Levelrange"
 //usage:	)
 
-#include <getopt.h>
 #include <selinux/context.h>
 #include <selinux/flask.h>