Defining developer targets for the configure phase

[Roland Illig <roland.illig%gmx.de@localhost>]

In mk/configure/configure.mk I found the useful target configure-help.
It is defined like this:

configure-help: # no dependencies here
        ${RUN} ./configure --help

In order to run the configure script, the package needs to be extracted
and patched first. I naively assumed that I could just make
configure-help depend on patch:

configure-help: patch
        ${RUN} ./configure --help

When I tested this, the package was completely built instead of just
doing everything up to the patch phase. How can I tell the pkgsrc make
to not build the package when I run "bmake configure-help"?