Add support for RTEMS 5.1 - sample_defs toolchain file updates

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Is your feature request related to a problem? Please describe.
The cFS Bundle currently supports RTEMS 4.11. Now that RTEMS 5.1 has been released, I would like to update the necessary components to support RTEMS 5.1 on the pc-rtems platform. This involves minor modifications to the cfe repository, the PSP repository, and the OSAL repository. These changes can be done in such a way that preserves the current RTEMS 4.11 support and adds RTEMS 5.1 support.

Describe the solution you'd like
For the cFE repository, the only changes needed are to the sample_defs toolchain files. I need to make a small modification to the 4.11 RTEMS toolchain file, and add a new toolchain file for RTEMS 5.

Describe alternatives you've considered
Alternatives include:

• Not supporting newer versions of RTEMS, but several projects will depend on RTEMS 5 support.
• Dropping RTEMS 4.11 support and just making the changes needed for RTEMS 5, but there may be projects that depend on RTEMS 4.11. We can consider dropping RTEMS 4.11 support on a future release.

Additional context

Requester Info
Alan Cudmore / NASA GSFC Code 582

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Related to
OSAL 608: nasa/osal#608
PSP 197: nasa/PSP#197