debian: support multiarch for libhandle

debian: support multiarch for libhandle

For nearly a decade now, Debian and derivatives have supported the
"multiarch" layout, where shared libraries are installed to
/lib/<gcc triple>/ instead of /lib.  This enables a single rootfs to
support binaries from multiple architectures (e.g. i386 inside an amd64
system).  We should follow this, since libhandle is useful.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>