[libvirt] xen-proxy build broken

Didn't have time to fix this today; virVirtualPortProfileFormat is conditionally implemented based on PROXY, but unconditionally called. Throwing it out there in case someone else wants to beat me to the fix. cc1: warnings being treated as errors ../src/conf/domain_conf.c: In function 'virDomainNetDefFormat': ../src/conf/domain_conf.c:5343: error: implicit declaration of function 'virVirtualPortProfileFormat' [-Wimplicit-function-declaration] ../src/conf/domain_conf.c:5343: error: nested extern declaration of 'virVirtualPortProfileFormat' [-Wnested-externs] -- Eric Blake eblake(a)redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org