Avoid copying and strlen(3) in the FindClass path.

Change-Id: I789f3c883596d1852a2c1954ce7a207e6f937117
diff --git a/src/dex_verifier_test.cc b/src/dex_verifier_test.cc
index a074b72..1c804af 100644
--- a/src/dex_verifier_test.cc
+++ b/src/dex_verifier_test.cc
@@ -16,7 +16,7 @@
  protected:
   void VerifyClass(ClassLoader* class_loader, const std::string& descriptor) {
     ASSERT_TRUE(descriptor != NULL);
-    Class* klass = class_linker_->FindSystemClass(descriptor);
+    Class* klass = class_linker_->FindSystemClass(descriptor.c_str());
 
     // Verify the class
     ASSERT_TRUE(DexVerifier::VerifyClass(klass));