Implement issetugid syscall

Implement issetugid syscall and provide a test. This gets rid of the
scary "Unsecure. Implement me" warning during compilation.

common/include/minix/callnr.h

@@ -100,7 +100,7 @@
 #define EXEC_RESTART	102	/* to PM: final part of exec for RS */
 #define PROCSTAT	103	/* to PM */
 #define GETPROCNR	104	/* to PM */
-
+#define ISSETUGID	106	/* to PM: ask if process is tainted */
 #define GETEPINFO_O	107	/* to PM: get pid/uid/gid of an endpoint */
 #define ADDDMA		108	/* to PM: inform PM about a region of memory
 				 * that is used for bus-master DMA

common/include/minix/type.h

@@ -165,6 +165,7 @@ struct exec_newmem
 	time_t enst_ctime;	/* Last changed time of executable file */
 	uid_t new_uid;		/* Process UID after exec */
 	gid_t new_gid;		/* Process GID after exec */
+	int setugid;		/* Process is setuid or setgid */
 	char progname[16];	/* Should be at least PROC_NAME_LEN */
 };