Reset stack after longjmp

[Abhishek21g]

Summary

• reset the inferred call stack when a longjmp-style symbol is called
• suppress return-underflow noise after the non-local jump until a normal call establishes a new stack
• recognize common libc/glibc variants, including versioned symbols such as longjmp@@GLIBC_...
• add an expect test for the longjmp symbol classifier

Fixes #35.

Notes

This intentionally does not try to reconstruct the exact skipped frames from setjmp/longjmp; the branch stream does not contain enough information to know how many frames were unwound. Instead, it follows the issue's suggested fallback: close the currently inferred stack and avoid fabricating noisy [unknown] frames from the unmatched rets that can follow.

Validation

• git diff --check
• make attempted locally, but this machine does not have dune installed:
  make: dune: No such file or directory

Linux validation still needed

dune build
dune runtest