perf symbols: Add machine id to modules debug message

Current debug message is:
Problems creating module maps, continuing anyway...

When running multiple VMs it would be nice to know which machine the
message is referring to:

$ perf kvm --guest --guestmount=/tmp/guest-mount record -av -- sleep 10
Problems creating module maps for guest 6613, continuing anyway...
Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1342826756-64663-2-git-send-email-dsahern@gmail.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/symbol.c

@@ -2564,8 +2564,15 @@ int machine__create_kernel_maps(struct machine *machine)
 	    __machine__create_kernel_maps(machine, kernel) < 0)
 		return -1;
 
-	if (symbol_conf.use_modules && machine__create_modules(machine) < 0)
-		pr_debug("Problems creating module maps, continuing anyway...\n");
+	if (symbol_conf.use_modules && machine__create_modules(machine) < 0) {
+		if (machine__is_host(machine))
+			pr_debug("Problems creating module maps, "
+				 "continuing anyway...\n");
+		else
+			pr_debug("Problems creating module maps for guest %d, "
+				 "continuing anyway...\n", machine->pid);
+	}
+
 	/*
 	 * Now that we have all the maps created, just set the ->end of them:
 	 */