private header grpc

Author: scotthart

.bazelrc

@@ -20,7 +20,7 @@ build --enable_platform_specific_config=true
 
 build --features=external_include_paths
 
-build --per_file_copt=grpc+//@-Wprivate
+build --per_file_copt=grpc+//@-Wprivate-header
 
 
 # The project requires C++ >= 17.