sysinit: Do not open console when just referencing reentrancy structure.

This change eliminates a system initialization dependentcy which resulted
in an application without a file system or console referencing errno being
forced to include the code to open(/dev/console), close(), atexit(),
and the unmount infrastructure.

Closes #4439.

cpukit/libcsupport/src/libio_init.c

@@ -65,9 +65,3 @@ RTEMS_SYSINIT_ITEM(
   RTEMS_SYSINIT_LIBIO,
   RTEMS_SYSINIT_ORDER_MIDDLE
 );
-
-RTEMS_SYSINIT_ITEM(
-  rtems_libio_post_driver,
-  RTEMS_SYSINIT_STD_FILE_DESCRIPTORS,
-  RTEMS_SYSINIT_ORDER_MIDDLE
-);