libxml binding: Fix static delegates
libxml binding: Fix static delegates

The syntax has changed from static delegate to [CCode (has_target=false)].
This commit fixes the libxml binding.

themiwi/vala,tjol/vala-tjol,playya/vala,rvu95/vala,GNOME/vala,spidermonkdust/vala,GNOME/vala,themiwi/vala,kamanashisroy/aroop,xdave/pvala,flobrosch/vala-fixes,Distrotech/vala,severinh/vala,playya/vala,severinh/vala,kamanashisroy/aroop,themiwi/vala,severinh/vala,frida/vala,rvu95/vala,jessevdk/vala,Distrotech/vala,frida/vala,tjol/vala-tjol,GNOME/vala,frida/vala,playya/vala,jessevdk/vala,flobrosch/vala-fixes,GNOME/vala,flobrosch/vala-fixes,frida/vala,spidermonkdust/vala,tjol/vala-tjol,frida/vala,kamanashisroy/aroop,Distrotech/vala,jessevdk/vala,spidermonkdust/vala,rvu95/vala