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

Bug: 30411878
Test: build with WITH_TIDY=1
Change-Id: I7fd815aa401fbcaff97b772f3ba5d6f1d2034011
diff --git a/tools/aapt2/dump/DumpManifest.cpp b/tools/aapt2/dump/DumpManifest.cpp
index 92f1ddb..42a6471 100644
--- a/tools/aapt2/dump/DumpManifest.cpp
+++ b/tools/aapt2/dump/DumpManifest.cpp
@@ -1175,7 +1175,7 @@
     }
 
     // Fully qualify the activity name
-    ssize_t idx = name.find(".");
+    ssize_t idx = name.find('.');
     if (idx == 0) {
       name = package + name;
     } else if (idx < 0) {
@@ -2125,7 +2125,7 @@
     size_t pos = file_path.find("lib/");
     if (pos != std::string::npos) {
       file_path = file_path.substr(pos + 4);
-      pos = file_path.find("/");
+      pos = file_path.find('/');
       if (pos != std::string::npos) {
         file_path = file_path.substr(0, pos);
       }