Make stuff build on openbsd

Make stuff build on openbsd

arch/alpha/alpha_tru64_process.cc:
    So, I don't know why linux uses an off_t here.
    I'm also not sure why linux defines an off_t to be a long
    Let's just use long here since it works for linux, and that's
    what bsd does
base/inifile.cc:
    correct #include for OpenBSD
dev/disk_image.cc:
    the correct type for this is streampos

--HG--
extra : convert_revision : f3ac3a3b8515d66e07ffb9780d8a9e387297b6a0