Fix performance-for-range-copy warnings

Bug: 30413223
Test: make with WITH_TIDY=1 DEFAULT_GLOBAL_TIDY_CHECKS=-*,performance*
Change-Id: Ie481e88025a7a1f3abde8ff63420d5ccd8577e52
diff --git a/tools/aapt2/cmd/Compile.cpp b/tools/aapt2/cmd/Compile.cpp
index 411ad74..0b43c5d 100644
--- a/tools/aapt2/cmd/Compile.cpp
+++ b/tools/aapt2/cmd/Compile.cpp
@@ -486,7 +486,7 @@
     }
 
     Printer r_txt_printer(&fout_text);
-    for (const auto res : xmlres->file.exported_symbols) {
+    for (const auto& res : xmlres->file.exported_symbols) {
       r_txt_printer.Print("default int id ");
       r_txt_printer.Println(res.name.entry);
     }