Fix path data number parsing

Previously highly-optimized path data was being garbled during loading.
A patch has been available for over four years.  Fix it.  This is pretty
much the same patch as one submitted by Louis Simard, which I verified
was correct except for two cases where it was using "&=" when "|=" was
intended.

https://bugzilla.gnome.org/show_bug.cgi?id=620923