config: Fix setting FSTYP automatically

config: Fix setting FSTYP automatically

Currently if the FSTYP is not set, the code to get FSTYP using blikd
would not work. This is because we're using HOSTOS environment variable
which might not be set (at least not on my system) and because it's
already late in the code path.

Fix this by using OSTYP environment variable as a fallback in the case
that HOSTOS does not work and move the check to common/config.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Tested-by: Filipe David Manana <fdmanana@gmail.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>