Fix memory error when dumping timings.

Use the pass name instead of a stack allocated std::string.

Change-Id: Ic87cf9cb7cc3c7bd847cc69c9aa1203d07136062
diff --git a/compiler/dex/pass_driver.cc b/compiler/dex/pass_driver.cc
index b20d728..99541ac 100644
--- a/compiler/dex/pass_driver.cc
+++ b/compiler/dex/pass_driver.cc
@@ -161,9 +161,7 @@
 
   // Do we perform a time split
   if (time_split == true) {
-    std::string name = "MIROpt:";
-    name += curPass->GetName();
-    c_unit->NewTimingSplit(name.c_str());
+    c_unit->NewTimingSplit(curPass->GetName());
   }
 
   // Check the pass gate first.