Return success status of grpc_byte_buffer_reader

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

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

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

include/grpc++/support/byte_buffer.h

include/grpc/impl/codegen/byte_buffer.h

src/core/lib/surface/byte_buffer_reader.c

src/cpp/common/core_codegen.cc

src/cpp/util/byte_buffer.cc

src/csharp/ext/grpc_csharp_ext.c

src/node/ext/byte_buffer.cc

src/objective-c/GRPCClient/private/NSData+GRPC.m

src/php/ext/grpc/byte_buffer.c

src/python/grpcio/grpc/_cython/_cygrpc/records.pyx.pxi

src/ruby/ext/grpc/rb_byte_buffer.c

test/core/end2end/cq_verifier.c

test/core/surface/byte_buffer_reader_test.c