Address a bunch of clang-tidy complaints.

There were a bunch more unreasonable/incorrect ones, but these ones
seemed legit. Nothing very interesting, though.

Bug: N/A
Test: ran tests, benchmarks
Change-Id: If66971194d4a7b4bf6d0251bedb88e8cdc88a76f
diff --git a/linker/linker.cpp b/linker/linker.cpp
index 317fdff..63415d8 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -3631,7 +3631,7 @@
   std::string error_msg;
 
   std::string ld_config_vndk = kLdConfigFilePath;
-  size_t insert_pos = ld_config_vndk.find_last_of(".");
+  size_t insert_pos = ld_config_vndk.find_last_of('.');
   if (insert_pos == std::string::npos) {
     insert_pos = ld_config_vndk.length();
   }