build: Add libxenctrl to LIBXL_LIBS
build: Add libxenctrl to LIBXL_LIBS

Commit dfa1e1dd removed libxenctrl from LIBXL_LIBS, but the libxl
driver uses a symbol from this library.  Explicitly link with
libxenctrl instead of relying on the build system to support
implicit DSO linking.

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