store "line count" buildstep data somewhere, draw graphs

[warner]

​http://tahoe-lafs.org/buildbot/builders/Kyle%20OpenBSD%20amd64/builds/306/steps/line-count/logs/stdio shows this builder not understanding whatever "wc" command arguments we're using to count lines.

Also, check to see that we're actually putting these results somewhere, maybe a database, since presumeably we've got a reason for counting them. I know I'm probably the one who added this step years ago, but I forget why. Were we counting TODOs?

[warner]

gmake count-lines
 in dir /storage/_buildbot/tahoe-lafs/Kyle OpenBSD amd64/build (timeout 1200 secs)
 watching logfiles {}
 argv: ['gmake', 'count-lines']
 environment:
  HOME=/storage/_buildbot
  LOGNAME=_buildbot
  PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/X11R6/bin:/usr/local/bin
  PWD=/storage/_buildbot/tahoe-lafs/Kyle OpenBSD amd64/build
  SHELL=/bin/sh
  USER=_buildbot
 closing stdin
 using PTY: False
files: wc: unknown option -- -
usage: wc [-c | -m] [-hlw] [file ...]
gmake: *** [count-lines] Error 1
program finished with exit code 2
elapsedTime=0.062026

[warner]

I fixed the buildstep, it's now on the "ubuntu-trusty" builder.

No storage for them yet, though.

[warner]

changing the purpose of this ticket to focus on the database/counting/graphing/analysis aspect.

[exarkun]

Why?