ART: Move JNI files to runtime/jni/ .

Test: Rely on TreeHugger.
Change-Id: I9cae11191ef1567ae9453be498882a7767285140
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 44445ae..4141a37 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -79,11 +79,11 @@
 #include "imtable-inl.h"
 #include "intern_table.h"
 #include "interpreter/interpreter.h"
-#include "java_vm_ext.h"
 #include "jit/debugger_interface.h"
 #include "jit/jit.h"
 #include "jit/jit_code_cache.h"
-#include "jni_internal.h"
+#include "jni/java_vm_ext.h"
+#include "jni/jni_internal.h"
 #include "linear_alloc.h"
 #include "mirror/call_site.h"
 #include "mirror/class-inl.h"