[aapt2] Improve dump chunks for string pools, fix diff

- `dump chunks` command now prints extra header data for the
  string pool, and outputs all style information for styled
  strings.

- `diff` command used to only correctly compare the first span
  in the StyledString data type, making them appear different
  if there was a string with more than one span

Flag: EXEMPT bugfix
Test: atest aapt2_tests
Change-Id: I377718c03d6a464cb4db22399b0f067e6a6e04d6
diff --git a/libs/androidfw/StringPool.cpp b/libs/androidfw/StringPool.cpp
index 1cb8df3..ad445c0 100644
--- a/libs/androidfw/StringPool.cpp
+++ b/libs/androidfw/StringPool.cpp
@@ -132,7 +132,7 @@
 
   auto rhs_iter = rhs.entry_->spans.begin();
   for (const Span& span : entry_->spans) {
-    const Span& rhs_span = *rhs_iter;
+    const Span& rhs_span = *rhs_iter++;
     if (span.first_char != rhs_span.first_char || span.last_char != rhs_span.last_char ||
         span.name != rhs_span.name) {
       return false;