https://qa.debian.org/bls/bytag/ RRD graphs should standardize axis

[Daniel Kahn Gillmor <dkg@fifthhorseman.net>]

I'm looking at the graphs in:

https://qa.debian.org/bls/bytag/W-dpkg-buildflags-missing.html

they seem to have an arbitrarily-placed vertical axis.  The bottom of
the graph should be 0, so that we can clearly see what proportion of
packages are lacking these build flags.

thanks for maintaining these charts!

       --dkg