util: reduce scope of a DIR * in virCgroupV1SetOwner()

util: reduce scope of a DIR * in virCgroupV1SetOwner()

DIR *dh is being re-used each time through the for loop of this
function, so it must be closed and then re-opened, which means we
can't convert it to g_autoptr. By moving the definition of dh inside
the for loop, we make it possible to trivially convert to g_autoptr
(which will happen in a subsequent patch)

NB: VIR_DIR_CLOSE() is already called at the bottom of the for loop,
so removing the VIR_DIR_CLOSE() at the end of the function is *not*
creating a leak of a DIR*!

Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>