package/pmake: force argv[0]=${0} in the pmake wrapper

This forces bmake to call the wrapper, not itself.
Also, use consistent "${0/*}" instead of "${0/pmake}".

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>