- Loop startup waitpid on EINTR; kill and reap the child on fatal error
or when interrupted, instead of leaking a ptrace-stopped process.
- Treat PTRACE_DETACH failure as fatal -- otherwise the child is stuck
stopped forever.
- Zero-initialize procName so the memcpy into ___tracy_magic_process_name
does not copy uninitialized stack past the NUL.
- Forward SIGINT to the child from the signal handler when in forked
mode, so Ctrl-C during a blocking waitpid unblocks cleanly.
- Preflight perf_event_open on the target before StartupProfiler so
permission failures surface with actionable guidance instead of
silently producing no samples.
- Also handle SIGHUP and SIGQUIT.
