GTlsCertificate: fix loading of chain with private key
GTlsCertificate: fix loading of chain with private key

If a private key (or anything, in fact) follows the final certificate in
the file, certificate parsing will be aborted and only the first
certificate in the chain will be returned, with the private key not set.
Be tolerant of this, rather than expecting the final character in the
file to be the newline following the last certificate.

https://bugzilla.gnome.org/show_bug.cgi?id=754264

ieei/glib,Distrotech/glib,cention-sany/glib,Distrotech/glib,johne53/MB3Glib,endlessm/glib,johne53/MB3Glib,endlessm/glib,johne53/MB3Glib,endlessm/glib,mzabaluev/glib,tchakabam/glib,johne53/MB3Glib,tchakabam/glib,Distrotech/glib,MathieuDuponchelle/glib,mzabaluev/glib,tchakabam/glib,MathieuDuponchelle/glib,cention-sany/glib,Distrotech/glib,MathieuDuponchelle/glib,cention-sany/glib,ieei/glib,cention-sany/glib,mzabaluev/glib,MathieuDuponchelle/glib,ieei/glib,tchakabam/glib,Distrotech/glib,johne53/MB3Glib,MathieuDuponchelle/glib,endlessm/glib,cention-sany/glib,mzabaluev/glib,tchakabam/glib,endlessm/glib,johne53/MB3Glib,mzabaluev/glib,ieei/glib,ieei/glib