rtems_sysmon does not build on RTEMS 4.11

[jphickey]

Describe the bug
The "rtems_sysmon" module is unconditionally included in the RTEMS PSP, but it does not build on 4.11 as it relies on functions that do not exist in this version.

To Reproduce
Build for RTEMS 4.11

Expected behavior
Should succeed

System observed on:
Debian with RTEMS 4.11 toolchain

Additional context
Simply disabling the rtems_sysmon module from psp_module_list.cmake allow RTEMS 4.11 to build again. However that is not a good general solution.

Better solution would be to add a bit of conditional logic such that the module is only included when the RTEMS version is >= 5.
That would fix the CFS RTEMS 4.11 workflows.

Reporter Info
Joseph Hickey, Vantage Systems, Inc.