Fix indentation of external_includes

This wasn't happening in the loop

Author: keith

clang_tidy/clang_tidy.bzl

@@ -70,7 +70,7 @@ def _run_tidy(
 
         args.add_all(compilation_context.system_includes.to_list(), before_each = "-isystem")
 
-    args.add_all(compilation_context.external_includes.to_list(), before_each = "-isystem")
+        args.add_all(compilation_context.external_includes.to_list(), before_each = "-isystem")
 
     ctx.actions.run(
         inputs = inputs,