PROTON-599: applied patch to fix typo on systems with SO_NOSIGPIPE

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1586183 13f79535-47bb-0310-9956-ffa450edef68
Do not assume there is just one element in CMAKE_MODULE_PATH
Do not redefine va_copy if not needed (for example, VS2013)
recv output is lost if aborted with ^C