I/O stats for lmtp, imap and pop

[Wesley Craig]

I don't see a good reason to include code that digs around in /proc when getrusage() has the exact same data.  I think adding, e.g., I/O to the telemetry calls would be peachy, either as a runtime option or if someone wants to exercise their autoconf-foo, at build time as appropriate to the platform in question.

When I wrote the getruage() code, I included only system & user CPU time because the platform I was working on provided them -- because POSIX requires them.  POSIX similarly requires that the other fields be present, but they didn't happen to have any content when I wrote that code, on the platform I was working on.  The present day version of the platform in question (Linux) provides much more data, and most non-Linux platforms have provided more than just CPU usage for many years.

:wes