gtlscertificate: fix certificate list parsing with trailing comments
gtlscertificate: fix certificate list parsing with trailing comments

g_tls_certificate_list_new_from_file() was supposed to ignore non-PEM
content, but it accidentally required that there not be anything after
the last certificate. Fix that.

https://bugzilla.gnome.org/show_bug.cgi?id=727692

lukasz-skalski/glib,johne53/MB3Glib,endlessm/glib,mzabaluev/glib,ieei/glib,lukasz-skalski/glib,Distrotech/glib,krichter722/glib,endlessm/glib,lukasz-skalski/glib,krichter722/glib,tchakabam/glib,johne53/MB3Glib,gale320/glib,Distrotech/glib,johne53/MB3Glib,krichter722/glib,lukasz-skalski/glib,mzabaluev/glib,MathieuDuponchelle/glib,ieei/glib,gale320/glib,krichter722/glib,cention-sany/glib,gale320/glib,johne53/MB3Glib,ieei/glib,Distrotech/glib,endlessm/glib,mzabaluev/glib,endlessm/glib,tchakabam/glib,MathieuDuponchelle/glib,endlessm/glib,Distrotech/glib,tamaskenez/glib,johne53/MB3Glib,cention-sany/glib,tchakabam/glib,tamaskenez/glib,ieei/glib,lukasz-skalski/glib,cention-sany/glib,mzabaluev/glib,johne53/MB3Glib,cention-sany/glib,tamaskenez/glib,tchakabam/glib,tchakabam/glib,tamaskenez/glib,gale320/glib,Distrotech/glib,MathieuDuponchelle/glib,krichter722/glib,gale320/glib,mzabaluev/glib,tamaskenez/glib,MathieuDuponchelle/glib,MathieuDuponchelle/glib,cention-sany/glib,ieei/glib