AAPT2: Fix pseudolocalization to respect <xliff:g>

The XLIFF 'g' tag specifies content that should NOT be translated.
AAPT2's pseudolocalization process should respect it.

Bug:34064599
Test: make libandroidfw_tests
Change-Id: Ice437d7f0ff246730ee04896fd035e2d846148fb
diff --git a/tools/aapt2/StringPool.h b/tools/aapt2/StringPool.h
index d0ce489..a626d37 100644
--- a/tools/aapt2/StringPool.h
+++ b/tools/aapt2/StringPool.h
@@ -70,6 +70,8 @@
     ~Ref();
 
     Ref& operator=(const Ref& rhs);
+    bool operator==(const Ref& rhs) const;
+    bool operator!=(const Ref& rhs) const;
     const std::string* operator->() const;
     const std::string& operator*() const;
 
@@ -93,6 +95,8 @@
     ~StyleRef();
 
     StyleRef& operator=(const StyleRef& rhs);
+    bool operator==(const StyleRef& rhs) const;
+    bool operator!=(const StyleRef& rhs) const;
     const StyleEntry* operator->() const;
     const StyleEntry& operator*() const;