add unit-test case for rvalue reference declarator
add unit-test case for rvalue reference declarator

Reviewed By: vitaut

Differential Revision: D23099543

fbshipit-source-id: a8c00f4679833f1ba272fbb885f7ba6386c94c08

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