Add SIGABRT monitoring support to segfault_analyzer

[saimizi]

What's changed

• Extended segfault_analyzer to monitor both SIGSEGV and SIGABRT signals
• Added support for detecting abort signals including stack smashing errors
• Updated data structures to include signal_number and event_type fields
• Modified BPF program to capture SIGABRT events with stack traces
• Enhanced output to display abort events with diagnostic information
• Stack traces for SIGABRT marked as potentially unreliable due to corruption
• Added test_stack_smashing.c test program compiled with -fstack-protector-strong
• Updated Makefile to build stack smashing test program
• Updated requirements.md and design.md to reflect simplified abort handling
• Users can identify stack smashing by examining stack trace for __stack_chk_fail

Key features:

• Captures complete stack traces for SIGABRT events
• Provides instruction pointer, registers, and VMA information
• Marks abort stack traces as potentially unreliable
• Simplified approach: all SIGABRT treated as 'ABORT' events
• Stack trace reveals abort cause (e.g., __stack_chk_fail for stack smashing)