dh_* tools can be invoked with "-p" option in the following ways:

    dh_installinit -v -pmypkg
    dh_installinit -v -p mypkg

Javahelper support only first variant:

    jh_depends -v -pmypkg

But it just do not do anything if there is a space between "-p" and
"mypkg":

    jh_depends -v -p mypkg

This behaviour is slightly confusing so it would be nice to recognise
DH-compatible syntax. Thanks.