src/libpcp/auxconnect.c: serialize getaddrinfo() calls
src/libpcp/auxconnect.c: serialize getaddrinfo() calls

According to helgrind (via qa/4751), getaddrinfo() is not threadsafe
so serialize with __pmLock_extcall lock/unlock.

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp