Log Message:
py-ICU: get it to build on NetBSD

There's more than one way to address the home-brewed build configuration
in use. For now, play along and add NetBSD to all the places that want
OS-specific entries. (Another way would be to populate all the
environment variables setup.py uses for alternate configuration sourcing
via the pkgsrc make file. Then we wouldn't have to patch setup.py at all.)

While here, also add TEST_DEPENDS entries.