Make AgentExtensions.h a true C header file
Make AgentExtensions.h a true C header file

By making it a C header languages such as Swift can use these calls directly instead of having to wrap them in extern C. I've removed the <string> include as it wasn't used, and changed the bool variables into ints. This change will need testing to make sure it doesn't break other runtimes (Node!)
RuntimeTools/omr-agentcore,RuntimeTools/omr-agentcore,RuntimeTools/omr-agentcore,RuntimeTools/omr-agentcore,RuntimeTools/omr-agentcore