Silence performance-avoid-endl check

We are not doing this anywhere performance critical.

Author: seanharmer

.clang-tidy

@@ -40,6 +40,7 @@ Checks: '*,
   -modernize-use-override,
   -modernize-use-trailing-return-type,
   -modernize-use-using,
+  -performance-avoid-endl,
   -readability-braces-around-statements,
   -readability-else-after-return,
   -readability-function-cognitive-complexity,