Make grpc++ independent of protobuf

BUILD

Makefile

build.yaml

include/grpc++/impl/codegen/core_codegen_interface.h

include/grpc++/impl/proto_utils.h

include/grpc++/support/config_protobuf.h

src/compiler/config.h

test/cpp/end2end/generic_end2end_test.cc

test/cpp/qps/parse_json.cc

test/cpp/qps/parse_json.h

test/cpp/qps/qps_json_driver.cc

test/cpp/util/byte_buffer_proto_helper.h

tools/doxygen/Doxyfile.c++

tools/doxygen/Doxyfile.c++.internal

tools/run_tests/sources_and_headers.json

vsprojects/vcxproj/grpc++/grpc++.vcxproj

vsprojects/vcxproj/grpc++/grpc++.vcxproj.filters

vsprojects/vcxproj/grpc++_test_util/grpc++_test_util.vcxproj

...vcxproj/grpc++_test_util/grpc++_test_util.vcxproj.filters

vsprojects/vcxproj/grpc++_unsecure/grpc++_unsecure.vcxproj