config(8): Flip the order of concatenation for hints and env

As previously noted, kernel's processing of these means that the first
appearance of a hint/variable wins. Flipping the order of concatenation
means that later variables override earlier variables, as expected when one
does:

hints x
hints y

Where perhaps x is:

hint.aw_sid.0.disable=1

and y is:

hint.aw_sid.0.disable=0

The expectation would be that a later appearing variable would override an
earlier appearing variable, such as with device/nodevice, device.hints,
and other similarly structured data files.