Fix #452, rtems sysmom overflow buffer

[avan989]

Fix #452, rtems sysmom coverage test causes an buffer overflow.

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• I reviewed the Contributing Guide.
• I signed and emailed the appropriate Contributor License Agreement to GSFC-SoftwareRelease@mail.nasa.gov and copied cfs-program@lists.nasa.gov.

Describe the contribution
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• Include explicitly what issue it addresses [e.g. Fixes #X]

Testing performed
Steps taken to test the contribution:

1. Run against RTEMS

2. Run unit test on linux

3. Make ENABLE_UNIT_TESTS=true SIMULATION=native

4. make install

5. make test

6. make lcov

Expected behavior changes
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• API Change: xxx (if applicable)
• Behavior Change: xxx (if applicable)
• Or no impact to behavior

System(s) tested on

• Hardware: [e.g. PC, SP0, MCP750]
• OS: [e.g. Ubuntu 18.04, RTEMS 4.11, VxWorks 6.9]
• Versions: [e.g. cFE 6.6, OSAL 4.2, PSP 1.3 for mcp750, any related apps or tools]

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  Anh Van, GSFC

[dzbaker]

CCB 3 April 2025: Provisionally approved pending rename of num_cpus variable.

[avan989]

updated.