Fix ARM64 compatibility with kernel version-aware VMA collection

[saimizi]

What's changed

Problem:

• bpf_find_vma helper (introduced in kernel 5.17) not available on older kernels
• BPF verifier rejects program with 'invalid func unknown#180' error
• ARM64 systems often run kernel 5.15.52 which lacks this helper

Solution:

• Add compile-time kernel version detection using LINUX_VERSION_CODE
• Implement dual VMA collection methods:
  • Kernel 5.17+: Use modern bpf_find_vma() helper (optimal performance)
  • Kernel <5.17: Use manual VMA walking via task->mm->mmap (compatibility)
• Automatic method selection at compile time
• Safety bounds (max 1000 VMAs) to prevent infinite loops
• File path extraction works on both implementation paths

Benefits:

• ARM64 compatibility on kernel 5.15.52
• Preserves VMA information for symbol resolution
• No performance regression on modern kernels
• Future-proof design with automatic detection
• Maintains all existing segfault analysis capabilities

The segfault analyzer now works on both modern and older kernel versions, automatically selecting the appropriate VMA collection method.

Fixes #46