[BZ#779405] Fix librsvg tarball builds (in particular Windows builds)
Submitted by Chun-wei Fan
It seems that during the course of development two things came into the librsvg sources, that led to release tarballs not to build:
-Added Rust sources that were not dist'ed. -Use of Pango-FT2, which is an optional component for Windows (unlike *NIX)
I will post patches to address these issues.
With blessings, thank you!