Revert "AAPT: Modified StringPool uniqueness detection"

This reverts commit 35ecb89a8aa68f24d2e991df5bb9964ad15075dc.

Reason for revert: <Long make duration (infinite loop)>

Change-Id: I10d1cf53ca3054d40e23b06368ebaff6af69beab
diff --git a/tools/aapt2/StringPool.cpp b/tools/aapt2/StringPool.cpp
index 73a8259..b0ce9e1 100644
--- a/tools/aapt2/StringPool.cpp
+++ b/tools/aapt2/StringPool.cpp
@@ -172,10 +172,9 @@
 StringPool::Ref StringPool::MakeRefImpl(const StringPiece& str, const Context& context,
                                         bool unique) {
   if (unique) {
-    for (auto& indexed_str : indexed_strings_) {
-      if (str == indexed_str.first && context.priority == indexed_str.second->context.priority) {
-        return Ref(indexed_str.second);
-      }
+    auto iter = indexed_strings_.find(str);
+    if (iter != std::end(indexed_strings_)) {
+      return Ref(iter->second);
     }
   }