PROTON-2145: install static cpp lib if enabled
PROTON-2145: install static cpp lib if enabled

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