Enable ARM SVE Support on Linux

[mohakgoel1]

Description

This PR enables Scalable Vector Extension (SVE) support for RocksDB on ARM-based Linux platforms. It introduces the necessary enablement logic while preserving existing behavior on non-SVE and non-Linux systems.

Key Changes

• Added SVE enablement logic for ARM-based Linux systems
• Verified build compatibility and functional correctness with existing configurations
• Ensured safe fallback to existing implementations when SVE is not available
• Prepared the groundwork for future SVE-based performance optimizations

Compatibility & Safety

• No behavior change on platforms without SVE support
• No impact on x86 or non-ARM architectures
• Linux-only enablement to avoid affecting unsupported environments

Testing

• Built and tested on ARM Linux systems

This PR is a joint contribution by:

• Abhishek Jain(@abhijain1204fujitsu)
• Mohak Goel(@mohakgoel1)

[mohakgoel1]

Hi @adamretter,

I hope you are doing well.
Whenever you have some time, could you please review my PR? I would really appreciate your feedback.
Thank you for your time and support.