Fix duplicate JIT frames on tail call re-entry

walk_ruby_stack is re-entered via tail calls to process more frames.
On re-entry, in_jit was recomputed from record->state.pc which hasn't
changed (non-FP path), causing the JIT frame to be pushed again on
every tail call. Guard with !jit_detected so the JIT frame is only
pushed once on the first entry.

Author: dalehamel

support/ebpf/ruby_tracer.ebpf.c

@@ -465,7 +465,8 @@ static EBPF_INLINE ErrorCode walk_ruby_stack(
   // When frame pointers are not available, we push a single dummy JIT frame and
   // set jit_detected to suppress native unwinding.
   bool in_jit = rubyinfo->jit_start > 0 && record->state.pc >= rubyinfo->jit_start &&
-                record->state.pc < rubyinfo->jit_end;
+                record->state.pc < rubyinfo->jit_end &&
+                !record->rubyUnwindState.jit_detected;
 
   if (in_jit) {
     if (rubyinfo->frame_pointers_enabled) {