PROTON-2484: epoll proactor - missing null pointer logic generously found by coverity
PROTON-2484: epoll proactor - missing null pointer logic generously found by coverity

astitcher/qpid-proton,apache/qpid-proton,apache/qpid-proton,astitcher/qpid-proton,gemmellr/qpid-proton,astitcher/qpid-proton,gemmellr/qpid-proton,gemmellr/qpid-proton,gemmellr/qpid-proton,apache/qpid-proton,astitcher/qpid-proton,gemmellr/qpid-proton,apache/qpid-proton,apache/qpid-proton,gemmellr/qpid-proton,apache/qpid-proton,astitcher/qpid-proton,astitcher/qpid-proton