add type annotations for the TCppServer.setPort() method
add type annotations for the TCppServer.setPort() method

Summary:
This method was not annotated initially in D22659651 (https://github.com/facebook/fbthrift/commit/2fbe2eb02666b8658823b97aa6b8a9350709489d).  Since it's used in a
few places let's go ahead and add an annotation for it.

Reviewed By: nanshu

Differential Revision: D23228737

fbshipit-source-id: bd599f948fa51a5461b768682c4144cf44269dcd

facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift