Move registration of AssetManager.mObject to zygote.

bug: 73865351
Test: m

Change-Id: I9d0f0c8ae016b8823246e25bfdbff0d4fd8eaae1
diff --git a/core/jni/android_util_AssetManager.cpp b/core/jni/android_util_AssetManager.cpp
index 7fa2247..fa9f445 100644
--- a/core/jni/android_util_AssetManager.cpp
+++ b/core/jni/android_util_AssetManager.cpp
@@ -75,9 +75,8 @@
   jfieldID mLength;
 } gAssetFileDescriptorOffsets;
 
-static struct assetmanager_offsets_t {
-  jfieldID mObject;
-} gAssetManagerOffsets;
+// This is also used by asset_manager.cpp.
+assetmanager_offsets_t gAssetManagerOffsets;
 
 static struct {
   jfieldID native_ptr;