Add compile-time tests for RTTI to port_def.inc
Add compile-time tests for RTTI to port_def.inc

This eliminates an ODR violation where users compile and install
Protobuf's C++ runtime without RTTI but do not define
GOOGLE_PROTOBUF_NO_RTTI when compiling their project with
the generated code.
google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf