Libs: migrate to SPDX identifier

[jerpelea]

Summary

Most tools used for compliance and SBOM generation use SPDX identifiers
This change brings us a step closer to an easy SBOM generation.
Some files were converted to Apache license

Ignored (will be evaluated later)
BSD-4-clause
libs/libc/stdlib/lib_bsearch.c
libs/libc/stdlib/lib_qsort.c

Impact

SPDX

Testing

CI

[nuttxpr]

[Experimental Bot, please feedback here]

This PR does not meet the NuttX requirements. Here's why:

Missing Information:

• Summary:
  • The specific functional code changes are unclear. Be explicit about what files were modified to include SPDX identifiers.
  • Explain how the changes bring you closer to SBOM generation.
• Impact:
  • Is new feature added? Is existing feature changed? - Unclear.
  • Impact on user: - Unclear. Will users interact with SBOM generation?
  • Impact on build: - Unclear. Does adding SPDX identifiers impact the build process itself?
  • Impact on hardware: - Unclear. Do SPDX additions impact any hardware dependencies?
  • Impact on documentation: - Documentation needs to be updated if you expect others to use the SBOM generation.
  • Impact on security: - Licensing changes have security implications. Address the BSD-4-clause files in this PR. "Evaluated later" is not acceptable.
  • Impact on compatibility: - Unclear. Do licensing changes affect compatibility with other software?
• Testing:
  • Build Host(s): - Provide specific details: OS, CPU architecture, compiler version.
  • Target(s): - Provide details: Specific architectures, boards, and configurations.
  • Testing logs before change/Testing logs after change: - These sections are empty. You must include logs to demonstrate the impact of your changes.

Recommendations:

1. Be Specific: Provide clear and detailed information about your changes in all sections.
2. Address Licensing: Do not defer licensing issues. The BSD-4-clause files need resolution within this PR.
3. Provide Evidence: Include testing logs that demonstrate the functionality before and after your changes.

Remember: A complete and informative PR will significantly speed up the review process.