tests/asv.c: exercise sliced-GValue constructors
tests/asv.c: exercise sliced-GValue constructors

As a bonus, this makes the original test more readable.

Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib