octave-svgconvert: Don't use Qt's SVG module (bug #59546) * acinclude.m4: Don't require QtSvg * octave-qsvghandler.h (toDouble, isDigit, parseNumbersArray, pathArcSegment, pathArc, parseTransformationMatrix, parsePathDataFast): New file. Set of static functions extracted from Qt-5.12 source code to build a QPainterPath from the "d" attribute of a "path" element. * module.mk: Include new header file in build system. * octave-svgconvert.cc (pdfpainter): Revert changes. (draw): Put back. Modify "g" element handler to account for potential "path", "text" or "use" children elements. Remove "tspan" element handler, which is no more needed, and refactor "text" element handler. Implement new "path" and "use" element handlers. (main): The DPI argument is no more needed. Just comment it out to eventually use it if we implement raster outputs.

--- a/m4/acinclude.m4	Fri Apr 09 09:38:40 2021 -0400
+++ b/m4/acinclude.m4	Wed Apr 07 22:21:36 2021 +0200
@@ -2031,7 +2031,7 @@
   case "$qt_version" in
     5)
       QT_OPENGL_MODULE="Qt5OpenGL"
-      QT_MODULES="Qt5Core Qt5Gui Qt5Help Qt5Network Qt5PrintSupport Qt5Svg Qt5Xml"
+      QT_MODULES="Qt5Core Qt5Gui Qt5Help Qt5Network Qt5PrintSupport Qt5Xml"
     ;;
     *)
       AC_MSG_ERROR([Unrecognized Qt version $qt_version])