ash: [PARSER] Fix parsing of ${##1}

ash: [PARSER] Fix parsing of ${##1}

Upstream commit:

    Date: Thu, 4 Oct 2007 22:15:10 +0800
    [PARSER] Fix parsing of ${##1}

    Previously dash treated ${##1} as a length operation.  This patch fixes that.

    Test case:

        set -- a
        echo ${##1}OK

    Old result:

        1OK

    New result:

        OK

This was a real bug in ash (but not in hush).

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>