Do not expose O_TMPFILE in a public header.

Adjust tst-open-tmpfile so that it exits with 0 in case of missing
kernel support.

Index: b/io/tst-open-tmpfile.c
===================================================================
--- a/io/tst-open-tmpfile.c
+++ b/io/tst-open-tmpfile.c
@@ -33,7 +33,6 @@ static int do_test (void);
 #define TEST_FUNCTION do_test ()
 #include "../test-skeleton.c"
 
-#ifdef O_TMPFILE
 typedef int (*wrapper_func) (const char *, int, mode_t);
 
 /* Error-checking wrapper for the open function, compatible with the
@@ -157,7 +156,7 @@ static void
 check_wrapper_flags_mode (const char *op, wrapper_func wrapper,
                           const char *path, int flags, mode_t mode)
 {
-  int fd = wrapper (path, flags | O_TMPFILE, mode);
+  int fd = wrapper (path, flags | __O_TMPFILE, mode);
   struct stat64 st;
   if (fstat64 (fd, &st) != 0)
     {
@@ -257,20 +256,20 @@ check_wrapper (const char *op, wrapper_f
 }
 
 /* Verify that the directory at PATH supports O_TMPFILE.  Exit with
-   status 77 (unsupported) if the kernel does not support O_TMPFILE.
-   Even with kernel support, not all file systems O_TMPFILE, so return
-   true if the directory supports O_TMPFILE, false if not.  */
+   status 0 if the kernel does not support O_TMPFILE.  Even with
+   kernel support, not all file systems O_TMPFILE, so return true if
+   the directory supports O_TMPFILE, false if not.  */
 static bool
 probe_path (const char *path)
 {
-  int fd = openat (AT_FDCWD, path, O_TMPFILE | O_RDWR, 0);
+  int fd = openat (AT_FDCWD, path, __O_TMPFILE | O_RDWR, 0);
   if (fd < 0)
     {
       if (errno == EISDIR)
         /* The system does not support O_TMPFILE.  */
         {
           printf ("info: kernel does not support O_TMPFILE\n");
-          exit (77);
+          exit (0);
         }
       if (errno == EOPNOTSUPP)
         {
@@ -291,29 +290,14 @@ do_test (void)
   const char *paths[] = { ".", "/dev/shm", "/tmp",
                           getenv ("TEST_TMPFILE_PATH"),
                           NULL };
-  bool supported = false;
   for (int i = 0; paths[i] != NULL; ++i)
     if (probe_path (paths[i]))
       {
-        supported = true;
         check_wrapper ("open", wrap_open, paths[i]);
         check_wrapper ("openat", wrap_openat, paths[i]);
         check_wrapper ("open64", wrap_open64, paths[i]);
         check_wrapper ("openat64", wrap_openat64, paths[i]);
       }
 
-  if (!supported)
-    return 77;
-
   return 0;
 }
-
-#else  /* !O_TMPFILE */
-
-static int
-do_test (void)
-{
-  return 77;
-}
-
-#endif  /* O_TMPFILE */
Index: b/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
===================================================================
--- a/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
+++ b/sysdeps/unix/sysv/linux/bits/fcntl-linux.h
@@ -131,7 +131,6 @@
 # define O_DIRECT	__O_DIRECT	/* Direct disk access.	*/
 # define O_NOATIME	__O_NOATIME	/* Do not set atime.  */
 # define O_PATH		__O_PATH	/* Resolve pathname but do not open file.  */
-# define O_TMPFILE	__O_TMPFILE	/* Atomically create nameless file.  */
 #endif
 
 /* For now, Linux has no separate synchronicitiy options for read