[RESTRICT AUTOMERGE] Move Theme::Entry definition to top of file

It needs to be at least above this line:

    theme->entries_.reserve(kInitialReserveSize);

Otherwise, after upgrading libc++, the compiler fails with errors about
an incomplete type, e.g.:

include/c++/v1/vector:839:62: error: arithmetic on a pointer to an incomplete type 'android::Theme::Entry'
include/c++/v1/__memory/uninitialized_algorithms.h:609:5: error: cannot increment value of type 'std::reverse_iterator<android::Theme::Entry *>'

Bug: b/175635923
Test: treehugger
Change-Id: I6c231184c3a4c0e67dd29d43560b0c28778883db
Merged-In: I6c231184c3a4c0e67dd29d43560b0c28778883db
diff --git a/libs/androidfw/AssetManager2.cpp b/libs/androidfw/AssetManager2.cpp
index fc9dd14..5777fb8 100644
--- a/libs/androidfw/AssetManager2.cpp
+++ b/libs/androidfw/AssetManager2.cpp
@@ -99,6 +99,13 @@
   StringPoolRef entry_string_ref;
 };
 
+struct Theme::Entry {
+  uint32_t attr_res_id;
+  ApkAssetsCookie cookie;
+  uint32_t type_spec_flags;
+  Res_value value;
+};
+
 AssetManager2::AssetManager2() {
   memset(&configuration_, 0, sizeof(configuration_));
 }
@@ -1411,13 +1418,6 @@
 
 Theme::~Theme() = default;
 
-struct Theme::Entry {
-  uint32_t attr_res_id;
-  ApkAssetsCookie cookie;
-  uint32_t type_spec_flags;
-  Res_value value;
-};
-
 namespace {
 struct ThemeEntryKeyComparer {
   bool operator() (const Theme::Entry& entry, uint32_t attr_res_id) const noexcept {