New stat structure.

* VFS and installed MFSes must be in sync before and after this change *

Use struct stat from NetBSD. It requires adding new STAT, FSTAT and LSTAT
syscalls. Libc modification is both backward and forward compatible.

Also new struct stat uses modern field sizes to avoid ABI
incompatibility, when we update uid_t, gid_t and company.
Exceptions are ino_t and off_t in old libc (though paddings added).

common/include/minix/callnr.h

@@ -17,7 +17,7 @@
 #define CHMOD		  15 
 #define CHOWN		  16 
 #define BRK		  17
-#define STAT		  18 
+#define PREV_STAT	  18
 #define LSEEK		  19
 #define MINIX_GETPID	  20
 #define MOUNT		  21 
@@ -27,7 +27,7 @@
 #define STIME		  25
 #define PTRACE		  26
 #define ALARM		  27
-#define FSTAT		  28 
+#define PREV_FSTAT	  28
 #define PAUSE		  29
 #define UTIME		  30 
 #define ACCESS		  33 
@@ -44,7 +44,7 @@
 #define GETGID		  47
 #define SIGNAL		  48
 #define RDLNK		  49
-#define LSTAT		  50
+#define PREV_LSTAT	  50
 #define IOCTL		  54
 #define FCNTL		  55
 #define FS_READY	  57
@@ -115,6 +115,11 @@
 
 #define GCOV_FLUSH	112	/* flush gcov data from server to gcov files */
 
+/* Numbers reused intentionally */
+#define STAT		65
+#define FSTAT		66
+#define LSTAT		67
+
 #define TASK_REPLY	121	/* to VFS: reply code from drivers, not 
 				 * really a standalone call.
 				 */

common/include/minix/type.h

@@ -167,7 +167,7 @@ struct exec_newmem
 	int is_elf;		/* Is ELF exe? */
 	dev_t st_dev;		/* Device holding executable file */
 	ino_t st_ino;		/* Inode of executable file */
-	time_t st_ctime;	/* Last changed time of executable file */
+	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 */
 	char progname[16];	/* Should be at least PROC_NAME_LEN */