chore: add debug output for /proc/maps in walltime

Print the benchmark process memory map when CODSPEED_DEBUG is enabled.
This helps with debugging missing symbols by showing which modules are
loaded at which addresses.

Author: not-matthias

src/executor/wall_time/perf/mod.rs

@@ -219,6 +219,16 @@ impl PerfRunner {
         let on_cmd = async |cmd: &FifoCommand| {
             #[allow(deprecated)]
             match cmd {
+                // Print /proc/{pid}/maps for the benchmark process. This helps with debugging missing symbols, as
+                // it allows finding the module in which an address is located.
+                FifoCommand::CurrentBenchmark { pid, .. } if is_codspeed_debug_enabled() => {
+                    let maps_path = format!("/proc/{pid}/maps");
+                    match std::fs::read_to_string(&maps_path) {
+                        Ok(maps) => debug!("/proc/{pid}/maps:\n{maps}"),
+                        Err(e) => debug!("Failed to read {maps_path}: {e}"),
+                    }
+                    return Ok(None);
+                }
                 FifoCommand::StartBenchmark => {
                     perf_fifo.start_events().await?;
                 }