Fix build.

Change-Id: I8bdc52e8557abc5b020ee19952fc45b0b95e09d9
diff --git a/src/jni_internal.cc b/src/jni_internal.cc
index 6cbf153..8485ced 100644
--- a/src/jni_internal.cc
+++ b/src/jni_internal.cc
@@ -632,7 +632,7 @@
   void* FindNativeMethod(const Method* m) {
     std::string jni_short_name(JniShortName(m));
     std::string jni_long_name(JniLongName(m));
-    ClassLoader* declaring_class_loader = m->GetDeclaringClass()->GetClassLoader();
+    const ClassLoader* declaring_class_loader = m->GetDeclaringClass()->GetClassLoader();
     for (It it = libraries_.begin(); it != libraries_.end(); ++it) {
       SharedLibrary* library = it->second;
       if (library->GetClassLoader() != declaring_class_loader) {