lvm2: make basic package available under musl

lvm2: make basic package available under musl

The basic lvm2 package (libdevmapper / dmsetup) does build under musl, only the
standard (full) installation doesn't.

Many setups only need the basic package, so move the !musl dependencies down
to the sub options and adjust the reverse dependencies (cryptsetup/dmraid)
to match.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
[Thomas: adjust Config.in comments and dependencies.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>