ssl: Improve error message in cert chain verification
ssl: Improve error message in cert chain verification

It contains the same information as before, but should be more readable.

Fantu/spice-common,SPICE/spice-common,freedesktop-unofficial-mirror/spice__spice-common,fgouget/spice-common,freedesktop-unofficial-mirror/spice__spice-common,freedesktop-unofficial-mirror/spice__spice-common,Fantu/spice-common,elmarco/spice-common,fgouget/spice-common,fgouget/spice-common,elmarco/spice-common,SPICE/spice-common,freedesktop-unofficial-mirror/spice__spice-common,elmarco/spice-common,elmarco/spice-common,Fantu/spice-common,fgouget/spice-common,Fantu/spice-common,SPICE/spice-common