4036 fix blkdev uninitialized return values (Makefile)

2933 compiler warning gags need better granularity
Reviewed by: Eric Schrock <eric.schrock@delphix.com>
Approved by: Garrett D'Amore <garrett@damore.org>

PSARC 2009/646 bd - generic block device driver
PSARC 2009/648 sdcard conversion to bd, EOF blk2scsa
6952618 deliver blkdev (PSARC 2009/646)