Fix clang-tidy performance-faster-string-find warnings

Bug: 30411878
Test: build with WITH_TIDY=1
Change-Id: I7fd815aa401fbcaff97b772f3ba5d6f1d2034011
diff --git a/tools/aapt2/java/ManifestClassGenerator.cpp b/tools/aapt2/java/ManifestClassGenerator.cpp
index 10e504e..09ea03b 100644
--- a/tools/aapt2/java/ManifestClassGenerator.cpp
+++ b/tools/aapt2/java/ManifestClassGenerator.cpp
@@ -39,7 +39,7 @@
   }
 
   // Normalize only the java identifier, leave the original value unchanged.
-  if (result.find("-") != std::string::npos) {
+  if (result.find('-') != std::string::npos) {
     result = JavaClassGenerator::TransformToFieldName(result);
   }