Don't call AddImageStringsToTable or MoveImageClassesToClassTable if running imageless

If we fail to create the image we use imageless running, this was
breaking AddImageStringsToTable since we didn't check for this
case. Added a check which avoids calling AddImageStringsToTable and
MoveImageClassesToClassTable if we don't have an image.

Bug: 18412472
Change-Id: I1dd8f306d5e41356a6b62fbd95315f564ee0d36e
diff --git a/runtime/intern_table.cc b/runtime/intern_table.cc
index 95c622a..29a2459 100644
--- a/runtime/intern_table.cc
+++ b/runtime/intern_table.cc
@@ -148,6 +148,7 @@
 }
 
 void InternTable::AddImageStringsToTable(gc::space::ImageSpace* image_space) {
+  CHECK(image_space != nullptr);
   MutexLock mu(Thread::Current(), *Locks::intern_table_lock_);
   if (!image_added_to_intern_table_) {
     mirror::Object* root = image_space->GetImageHeader().GetImageRoot(ImageHeader::kDexCaches);