Consistently tag libasan with gcc=48
Avoid stack overflow when SACK and TCP_SIGNATURE are both present. Thanks
to Jonathan Looney for pointing this out.
Support wedge names.

before:
    newfs dk1        - formats /dev/rdk1
    newfs rdk1       - cannot open /dev/rrdk1
    newfs /dev/dk1   - /dev/dk1 is a block-device, use raw device
    newfs /dev/rdk1  - formats /dev/rdk1

now:
    newfs dk1        - formats /dev/rdk1
    newfs rdk1       - cannot open /dev/rrdk1
    newfs /dev/dk1   - formats /dev/rdk1 (*)
    newfs /dev/rdk1  - formats /dev/rdk1
    newfs NAME=wedge - formats /dev/rdk1

(*) getfsspecname() returns the block device which must be translated.
    Passing a block device manually cannot be distinguished from this case.
Fix typo. Use format string.