PROTON-1391: Fix passing NULL as a var_arg not working on Solaris
PROTON-1391: Fix passing NULL as a var_arg not working on Solaris

ChugR/qpid-proton,ssorj/qpid-proton,kgiusti/qpid-proton,kgiusti/qpid-proton,alanconway/qpid-proton,ssorj/qpid-proton,apache/qpid-proton,alanconway/qpid-proton,ssorj/qpid-proton,gemmellr/qpid-proton,astitcher/qpid-proton,kgiusti/qpid-proton,ChugR/qpid-proton,gemmellr/qpid-proton,ChugR/qpid-proton,apache/qpid-proton,alanconway/qpid-proton,astitcher/qpid-proton,gemmellr/qpid-proton,ChugR/qpid-proton,alanconway/qpid-proton,astitcher/qpid-proton,ChugR/qpid-proton,gemmellr/qpid-proton,apache/qpid-proton,kgiusti/qpid-proton,gemmellr/qpid-proton,kgiusti/qpid-proton,gemmellr/qpid-proton,kgiusti/qpid-proton,astitcher/qpid-proton,apache/qpid-proton,alanconway/qpid-proton,astitcher/qpid-proton,ssorj/qpid-proton,astitcher/qpid-proton,apache/qpid-proton,ssorj/qpid-proton,apache/qpid-proton,alanconway/qpid-proton,ChugR/qpid-proton,ssorj/qpid-proton