Partially revert r227233.

The privs.h header is not only used by at(1), it's also used by
atrun(8). Just let the code the way it used to be (for now).

Reported by:	kwm, tinderbox
Hat to:		me

usr.bin/at/at.c

@@ -63,6 +63,8 @@ __FBSDID("$FreeBSD$");
 #include "panic.h"
 #include "parsetime.h"
 #include "perm.h"
+
+#define MAIN
 #include "privs.h"
 
 /* Macros */
@@ -102,8 +104,6 @@ int fcreated;
 char atfile[] = ATJOB_DIR "12345678901234";
 char atverify = 0;		/* verify time instead of queuing job */
 char *namep;
-uid_t real_uid, effective_uid;
-gid_t real_gid, effective_gid;
 
 /* Function declarations */
 

usr.bin/at/privs.h

@@ -59,8 +59,15 @@
  * to the real userid before calling any of them.
  */
 
-extern uid_t real_uid, effective_uid;
-extern gid_t real_gid, effective_gid;
+#ifndef MAIN
+extern
+#endif
+uid_t real_uid, effective_uid;
+
+#ifndef MAIN 
+extern
+#endif
+gid_t real_gid, effective_gid;
 
 #define RELINQUISH_PRIVS { \
 	real_uid = getuid(); \