A few fixes to AssetManager2 for compat

Theme copying should behave the way it did with the old AssetManager
(copy only the framework attributes when copying from a Theme object
from a different AssetManager).

Cleanup the dependencies on libziparchive in ApkAssets.

Test: make libandroidfw_tests
Test: out/host/<platform>/nativetests64/libandroidfw_tests/libandroidfw_tests --testdata=frameworks/base/libs/androidfw/tests/data
Change-Id: I973f7e6eb14ce311306e2ec66a623a4790c8d233
diff --git a/libs/androidfw/ApkAssets.cpp b/libs/androidfw/ApkAssets.cpp
index a5b1d29..0e577d1 100644
--- a/libs/androidfw/ApkAssets.cpp
+++ b/libs/androidfw/ApkAssets.cpp
@@ -30,6 +30,8 @@
 
 namespace android {
 
+ApkAssets::ApkAssets() : zip_handle_(nullptr, ::CloseArchive) {}
+
 std::unique_ptr<const ApkAssets> ApkAssets::Load(const std::string& path, bool system) {
   return ApkAssets::LoadImpl(path, system, false /*load_as_shared_library*/);
 }