As discussed in #14.
Current librsvg is used to render OT-SVG glyphs. However, librsvg is far from simple to build as it requires tons of transitive dependencies, especially on Windows.
Therefore, we could introduce a configure switch in the meson script to switch
librsvg on or off. This is trivial because the source code itself already
enable_librsvgoption, defaulting to
meson.build: Honor the option above.