gnutls: fix numerous errors preventing gnutls from being usable.
gnutls: fix numerous errors preventing gnutls from being usable.

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