mingw: workaround weird openssl build failure
mingw: workaround weird openssl build failure

If X509_NAME isn't undefined before including x509v3.h, very
weird compilation error occurs. It seems to be caused by duplicate
definitions for this symbols coming from wincrypto.h

fgouget/spice,mathslinux/spice,alon/spice-server,Fantu/spice,SPICE/spice,fgouget/spice,elmarco/spice,elmarco/spice,alon/spice-server,mathslinux/spice,mathslinux/spice,dezelin/spice,freedesktop-unofficial-mirror/spice__spice,ya-mouse/spice,dezelin/spice,fgouget/spice,freedesktop-unofficial-mirror/spice__spice,ya-mouse/spice,Fantu/spice,dezelin/spice,freedesktop-unofficial-mirror/spice__spice,alon/spice-server,alon/spice-server,freedesktop-unofficial-mirror/spice__spice,dezelin/spice,SPICE/spice,Fantu/spice,mathslinux/spice,Fantu/spice,elmarco/spice,SPICE/spice,elmarco/spice,freedesktop-unofficial-mirror/spice__spice,fgouget/spice,mathslinux/spice,alon/spice-server,ya-mouse/spice,dezelin/spice,elmarco/spice