[cairo] Holiday cleanup

[Sasha Kovar]

.-- Emmanuel Pacaud:
| Did you try to set the librsvg dpi to 72 (rsvg_set_default_dpi) ? With
| this setting, 1 pixel = 1 point. That's what we do when converting SVG
| files to PNG in the cairo test suite.

I'll try that.  Thanks.
 
| It's too late for a change of the default unit, and we should not change
| the API. If the librsvg dpi change doesn't solve your issue, a patch
| that would add a way to change the unit for the SVG document could be
| accepted.

Understood.  I may hack together a patch for this regardless.  Not that I
want to be an apologist for pixels as a unit of measure, but all of my code
so far has been using pixels as the default or explicit unit.  Illustrator,
FWIW, outputs svgs using explicit pixel measurements.  I'm keen to keep the
consistency.

Thank you both for your help.
Sasha