320ec7fa7f
Despite our attempt (build-docs.sh) to build the documentation with SVG, it still uses PNG https://llvm.org/doxygen/classllvm_1_1StringRef.html, and that renders terribly on any high dpi display. SVG leads to smasller installation and works fine on all browser (that has been true for _a while_ https://caniuse.com/svg), so this patch just unconditionally build all dot graphs as SVG in all subprojects and remove the option.