soup-auth-ntlm: fix build with --without-ntlm-auth
soup-auth-ntlm: fix build with --without-ntlm-auth

https://bugzilla.gnome.org/show_bug.cgi?id=710267

Distrotech/libsoup,Distrotech/libsoup,Distrotech/libsoup,Distrotech/libsoup,Distrotech/libsoup