[libc] Swap order of syscall on chmod (#138427)

We define SYS_fchmodat2 on libc but the syscall is not available on old
kernels, so prefer the SYS_fchmodat version when possible.

Author: mikhailramalho

libc/src/sys/stat/linux/chmod.cpp

@@ -23,12 +23,12 @@ namespace LIBC_NAMESPACE_DECL {
 LLVM_LIBC_FUNCTION(int, chmod, (const char *path, mode_t mode)) {
 #ifdef SYS_chmod
   int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_chmod, path, mode);
-#elif defined(SYS_fchmodat2)
-  int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_fchmodat2, AT_FDCWD, path,
-                                              mode, 0, AT_SYMLINK_NOFOLLOW);
 #elif defined(SYS_fchmodat)
   int ret =
       LIBC_NAMESPACE::syscall_impl<int>(SYS_fchmodat, AT_FDCWD, path, mode, 0);
+#elif defined(SYS_fchmodat2)
+  int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_fchmodat2, AT_FDCWD, path,
+                                              mode, 0, AT_SYMLINK_NOFOLLOW);
 #else
 #error "chmod, fchmodat and fchmodat2 syscalls not available."
 #endif