perf tools: Fix session init on non-modular kernels

perf top and perf record refuses to initialize on non-modular kernels:
refuse to initialize:

 $ perf top -v
  map_groups__set_modules_path_dir: cannot open /lib/modules/2.6.33-rc6-tip-00586-g398dde3-dirty/

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1265223128-11786-1-git-send-email-acme@infradead.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

tools/perf/util/symbol.c

@@ -1937,7 +1937,7 @@ int map_groups__create_kernel_maps(struct map_groups *self,
 		return -1;
 
 	if (symbol_conf.use_modules && map_groups__create_modules(self) < 0)
-		return -1;
+		return 0;
 	/*
 	 * Now that we have all the maps created, just set the ->end of them:
 	 */