ART: Add OnLoad system classloader search support

Add support for extension of the system classloader search path
during the OnLoad phase. Add test.

Bug: 34359699
Test: m test-art-host-run-test-936-search-onload
Change-Id: Ie0a5b4bb77999dfae87f955dde40b73ffe053b8e
diff --git a/runtime/openjdkjvmti/ti_search.h b/runtime/openjdkjvmti/ti_search.h
index 6a52e80..cd7b4be 100644
--- a/runtime/openjdkjvmti/ti_search.h
+++ b/runtime/openjdkjvmti/ti_search.h
@@ -32,12 +32,17 @@
 #ifndef ART_RUNTIME_OPENJDKJVMTI_TI_SEARCH_H_
 #define ART_RUNTIME_OPENJDKJVMTI_TI_SEARCH_H_
 
+#include <vector>
+
 #include "jvmti.h"
 
 namespace openjdkjvmti {
 
 class SearchUtil {
  public:
+  static void Register();
+  static void Unregister();
+
   static jvmtiError AddToBootstrapClassLoaderSearch(jvmtiEnv* env, const char* segment);
 
   static jvmtiError AddToSystemClassLoaderSearch(jvmtiEnv* env, const char* segment);