ART: Clean up strings fixup for app images.

This is a follow-up to
    https://android-review.googlesource.com/199854 .

Bug: 26846419
Bug: 22858531
Change-Id: Ib2b2c299c51686afb7f297697125296705ed77b8
diff --git a/runtime/utils/dex_cache_arrays_layout-inl.h b/runtime/utils/dex_cache_arrays_layout-inl.h
index d63083c..f6ee6a2 100644
--- a/runtime/utils/dex_cache_arrays_layout-inl.h
+++ b/runtime/utils/dex_cache_arrays_layout-inl.h
@@ -87,13 +87,11 @@
 }
 
 inline size_t DexCacheArraysLayout::StringsSize(size_t num_elements) const {
-  // App image patching relies on having enough room for a forwarding pointer in the types array.
-  return std::max(ArraySize(sizeof(GcRoot<mirror::String>), num_elements), pointer_size_);
+  return ArraySize(sizeof(GcRoot<mirror::String>), num_elements);
 }
 
 inline size_t DexCacheArraysLayout::StringsAlignment() const {
-  // App image patching relies on having enough room for a forwarding pointer in the strings array.
-  return pointer_size_;
+  return alignof(GcRoot<mirror::String>);
 }
 
 inline size_t DexCacheArraysLayout::FieldOffset(uint32_t field_idx) const {