Add android_dlwarning() method

This is temporary method intended to use
for a toast message on preview and beta
releases. Will be removed before the
production release.

Bug: http://b/27365747
Change-Id: I39cc716bb82863ae761b6821bcec77cce6db3781
diff --git a/linker/linker_dlwarning.h b/linker/linker_dlwarning.h
new file mode 100644
index 0000000..b67032c
--- /dev/null
+++ b/linker/linker_dlwarning.h
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __LINKER_DLWARNING_H
+#define __LINKER_DLWARNING_H
+
+void add_dlwarning(const char* sopath, const char* message, const char* value = nullptr);
+
+// Resets the current one (like dlerror but instead of
+// being thread-local it is process-local).
+const char* get_dlwarning();
+
+#endif  /* __LINKER_DLWARNING_H */