Do not encode entities in XML attributes
Do not encode entities in XML attributes

libxml2 will properly escape < > and " in XML attribute content. If
we use xmlEncodeEntitiesReentrant for attributes, this causes issues
with UTF8 filenames (gvir_config_domain_disk_set_source for example):
the filename UTF8 characters will be substituted with entities
(é -> &#xE9;), but when it uses this filename, libvirt will use it as
is and will fail to find the file.
I've tested that with this change gnome-boxes can open ISOs in directories
with 'é' in their names, and in directories with '&foo;xx<' in their names.

JGulic/libvirt-glib,libvirt/libvirt-glib,libvirt/libvirt-glib,JGulic/libvirt-glib,JGulic/libvirt-glib,JGulic/libvirt-glib,libvirt/libvirt-glib,JGulic/libvirt-glib