qemu_driver.c: use g_autoptr() when possible
qemu_driver.c: use g_autoptr() when possible

Several pointer types can be auto-unref for the great majority
of the uses made in qemu_driver, sparing us a virObjectUnref()
call.

This patch uses g_autoptr() in the following pointer types inside
qemu_driver.c, whenever possible:

- qemuBlockJobDataPtr
- virCapsPtr
- virConnect
- virDomainCapsPtr
- virNetworkPtr
- virQEMUDriverConfigPtr

Suggested-by: Erik Skultety <2c14d38fa47c8799f1b9c16280abe27f8edfec6e@redhat.com>
Signed-off-by: Daniel Henrique Barboza <627b089ad62deae9aaf06ccfa2c9056df28927e0@gmail.com>
Reviewed-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

jardasgit/libvirt,nertpinx/libvirt,libvirt/libvirt,crobinso/libvirt,jardasgit/libvirt,libvirt/libvirt,jfehlig/libvirt,olafhering/libvirt,crobinso/libvirt,libvirt/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,zippy2/libvirt,fabianfreyer/libvirt,crobinso/libvirt,nertpinx/libvirt,jardasgit/libvirt,zippy2/libvirt,crobinso/libvirt,libvirt/libvirt,zippy2/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,olafhering/libvirt,nertpinx/libvirt,zippy2/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,nertpinx/libvirt,jfehlig/libvirt,nertpinx/libvirt,olafhering/libvirt,olafhering/libvirt,jfehlig/libvirt,jardasgit/libvirt