AAPT2: Fix issue with parsing escape sequences when the parser only gives us part at a time

Change-Id: I671955f350b57577a991dd88f6a7319ec0b36c07
diff --git a/tools/aapt2/Util.h b/tools/aapt2/Util.h
index 9cdb152..7ec6b03 100644
--- a/tools/aapt2/Util.h
+++ b/tools/aapt2/Util.h
@@ -162,6 +162,7 @@
     std::u16string mStr;
     bool mQuote = false;
     bool mTrailingSpace = false;
+    bool mLastCharWasEscape = false;
     std::string mError;
 };