Pass a char instead of a string to the find function. clang-tidy: performance-faster-string-find

llvm-svn: 293379
diff --git a/clang/lib/Frontend/Rewrite/RewriteObjC.cpp b/clang/lib/Frontend/Rewrite/RewriteObjC.cpp
index e842e59..934d6aa 100644
--- a/clang/lib/Frontend/Rewrite/RewriteObjC.cpp
+++ b/clang/lib/Frontend/Rewrite/RewriteObjC.cpp
@@ -3629,7 +3629,7 @@
   Name += "__" + MD->getSelector().getAsString();
   // Convert colons to underscores.
   std::string::size_type loc = 0;
-  while ((loc = Name.find(":", loc)) != std::string::npos)
+  while ((loc = Name.find(':', loc)) != std::string::npos)
     Name.replace(loc, 1, "_");
 }