perf trace: Free the host machine allocation

trace__symbols_init() creates the host machine with machine__new_host(),
which allocates a struct machine, but trace__symbols__exit() released it
with machine__exit(). That tears down the contents of the machine and
leaves the allocation itself behind, so use machine__delete(), which
does both. The replay path points trace->host at the machine embedded in
the session and never reaches here, so nothing else is affected.

The leak was hidden from leak sanitizer because trace__symbols_init()
passes the machine to trace_event__register_resolver(), which stores it
as the private pointer of the global tep handle. The handle kept the
machine reachable for as long as the process lived, so it was only once
the handle started being freed that this was reported:

  Direct leak of 1256 byte(s) in 1 object(s) allocated from:
      #1 __machine__new_host util/machine.c:135
      #2 machine__new_host util/machine.c:155
      #3 trace__symbols_init builtin-trace.c:2105
      #4 trace__run builtin-trace.c:4759
      #5 cmd_trace builtin-trace.c:6091

Assisted-by: Antigravity:gemini-3.1-pro
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -2138,7 +2138,7 @@ static int trace__symbols_init(struct trace *trace, int argc, const char **argv,
 
 static void trace__symbols__exit(struct trace *trace)
 {
-	machine__exit(trace->host);
+	machine__delete(trace->host);
 	trace->host = NULL;
 
 	perf_env__exit(&trace->host_env);