bpo-44849: Fix os.set_inheritable() on FreeBSD 14 with O_PATH (GH-27623)

Fix the os.set_inheritable() function on FreeBSD 14 for file
descriptor opened with the O_PATH flag: ignore the EBADF error on
ioctl(), fallback on the fcntl() implementation.

Misc/NEWS.d/next/Library/2021-08-06-13-00-28.bpo-44849.O78F_f.rst

@@ -0,0 +1,4 @@
+Fix the :func:`os.set_inheritable` function on FreeBSD 14 for file descriptor
+opened with the :data:`~os.O_PATH` flag: ignore the :data:`~errno.EBADF`
+error on ``ioctl()``, fallback on the ``fcntl()`` implementation. Patch by
+Victor Stinner.

Python/fileutils.c

@@ -1374,10 +1374,11 @@ set_inheritable(int fd, int inheritable, int raise, int *atomic_flag_works)
             return 0;
         }
 
-#ifdef __linux__
+#ifdef O_PATH
         if (errno == EBADF) {
-            // On Linux, ioctl(FIOCLEX) will fail with EBADF for O_PATH file descriptors
-            // Fall through to the fcntl() path
+            // bpo-44849: On Linux and FreeBSD, ioctl(FIOCLEX) fails with EBADF
+            // on O_PATH file descriptors. Fall through to the fcntl()
+            // implementation.
         }
         else
 #endif