Function is_valid_elf 

fn is_valid_elf(data: &[u8]) -> bool

Validate that a buffer looks like a valid ELF header.

Checks:

• Magic: 0x7F ‘E’ ‘L’ ‘F’
• Class: 32-bit (1) or 64-bit (2)
• Data: little-endian (1)
• Type: relocatable (1), executable (2), shared (3), or core (4)