debian: don't bypass top level Makefile when building subdirs

debian: don't bypass top level Makefile when building subdirs

The top level Makefile does some processing to set build environment
variables (Q and CHECK_CMD).  debian/rules uses -C to build subdirs
directly, which bypases this feature of the top-level makefile, which
causes more build spew than necessary (because Q never gets set to quiet
the build).

Since the top level makefile can be used to build the subdirs
debian/rules cares about, drop the -C and build subdirs via the top
level Makefile to quiet the build.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Nathan Scott <nathans@debian.org>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>