build: fix virdbus build on mingw
build: fix virdbus build on mingw

Mingw headers pollute the namespace.

  CC       libvirt_util_la-virdbus.lo
../../src/util/virdbus.c:1102:35: error: expected ';', ',' or ')' before 'struct'
                       const char *interface,
                                   ^

* src/util/virdbus.c (virDBusCallMethod): Avoid 'interface'.

Signed-off-by: Eric Blake <a9da18479c871fe903d9590822cfe2629c6a4d11@redhat.com>

shugaoye/libvirt,zhlcindy/libvirt-1.1.4-maintain,shugaoye/libvirt,eskultety/libvirt,nertpinx/libvirt,jardasgit/libvirt,cbosdo/libvirt,jfehlig/libvirt,taget/libvirt,zhlcindy/libvirt-1.1.4-maintain,zhlcindy/libvirt-1.1.4-maintain,crobinso/libvirt,libvirt/libvirt,olafhering/libvirt,taget/libvirt,jfehlig/libvirt,libvirt/libvirt,VenkatDatta/libvirt,cbosdo/libvirt,eskultety/libvirt,nertpinx/libvirt,crobinso/libvirt,andreabolognani/libvirt,elmarco/libvirt,nertpinx/libvirt,eskultety/libvirt,nertpinx/libvirt,andreabolognani/libvirt,taget/libvirt,agx/libvirt,agx/libvirt,zippy2/libvirt,zippy2/libvirt,shugaoye/libvirt,fabianfreyer/libvirt,VenkatDatta/libvirt,datto/libvirt,taget/libvirt,olafhering/libvirt,eskultety/libvirt,shugaoye/libvirt,rlaager/libvirt,andreabolognani/libvirt,rlaager/libvirt,rlaager/libvirt,taget/libvirt,zippy2/libvirt,fabianfreyer/libvirt,zhlcindy/libvirt-1.1.4-maintain,jardasgit/libvirt,zhlcindy/libvirt-1.1.4-maintain,zippy2/libvirt,elmarco/libvirt,elmarco/libvirt,libvirt/libvirt,olafhering/libvirt,datto/libvirt,rlaager/libvirt,jfehlig/libvirt,crobinso/libvirt,VenkatDatta/libvirt,VenkatDatta/libvirt,rlaager/libvirt,eskultety/libvirt,datto/libvirt,elmarco/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,crobinso/libvirt,cbosdo/libvirt,cbosdo/libvirt,VenkatDatta/libvirt,nertpinx/libvirt,jardasgit/libvirt,jfehlig/libvirt,andreabolognani/libvirt,agx/libvirt,cbosdo/libvirt,shugaoye/libvirt,datto/libvirt,andreabolognani/libvirt,olafhering/libvirt,jardasgit/libvirt,agx/libvirt,fabianfreyer/libvirt,libvirt/libvirt,agx/libvirt,elmarco/libvirt,datto/libvirt,fabianfreyer/libvirt