std.Io.Threaded: fix compilation on s390x, hexagon, or1k, m68k

Apparently the O_TMPFILE flag is split across two bits on these
architectures and missing on m68k.

lib/std/Io/Threaded.zig

@@ -3430,6 +3430,17 @@ fn dirCreateFileAtomic(
     // useless when we have to make up a bogus path name to do the rename()
     // anyway.
     if (native_os == .linux and !options.replace) tmpfile: {
+        const flags: posix.O = if (@hasField(posix.O, "TMPFILE")) .{
+            .ACCMODE = .RDWR,
+            .TMPFILE = true,
+            .CLOEXEC = true,
+        } else if (@hasField(posix.O, "TMPFILE0") and !@hasField(posix.O, "TMPFILE2")) .{
+            .ACCMODE = .RDWR,
+            .TMPFILE0 = true,
+            .TMPFILE1 = true,
+            .CLOEXEC = true,
+        } else break :tmpfile;
+
         const dest_dirname = Dir.path.dirname(dest_path);
         if (dest_dirname) |dirname| {
             // This has a nice side effect of preemptively triggering EISDIR or
@@ -3456,12 +3467,6 @@ fn dirCreateFileAtomic(
         var path_buffer: [posix.PATH_MAX]u8 = undefined;
         const sub_path_posix = try pathToPosix(dest_dirname orelse ".", &path_buffer);
 
-        const flags: posix.O = .{
-            .ACCMODE = .RDWR,
-            .TMPFILE = true,
-            .CLOEXEC = true,
-        };
-
         const syscall: Syscall = try .start();
         while (true) {
             const rc = openat_sym(dir.handle, sub_path_posix, flags, options.permissions.toMode());

lib/std/os/linux.zig

@@ -459,13 +459,14 @@ pub const O = switch (native_arch) {
         NOFOLLOW: bool = false,
         NOATIME: bool = false,
         CLOEXEC: bool = false,
-        _20: u1 = 0,
+        TMPFILE0: bool = false,
         PATH: bool = false,
-        _22: u10 = 0,
+        _22: u4 = 0,
+        TMPFILE1: bool = false,
+        _27: u5 = 0,
 
         // #define O_RSYNC    04010000
         // #define O_SYNC     04010000
-        // #define O_TMPFILE 020200000
         // #define O_NDELAY O_NONBLOCK
     },
     .m68k => packed struct(u32) {