From Jeffrey Morlan: If a readpst child process fails with a nonzero status code for whatever reason (killed, segfault, out-of-memory, ...) the parent process will continue and likely end up exiting with status 0, tricking the caller into thinking readpst was successful when it was not.

Need testing on big-endian machines. We may be missing some LEnn_CPU()
calls.

pst2diii needs header and mime type updates from readpst.

At the next soname bump (to libpst.so.5) we should
    move some of readpst into the shared library, in particular write_normal_email()