Marker: fix MathJax rendering

It have never worked before.

srcpkgs/Marker/patches/system-mathjax.patch

@@ -0,0 +1,12 @@
+--- a/src/marker-markdown.c
++++ b/src/marker-markdown.c
+@@ -87,8 +87,7 @@ char* html_header(MarkerMathJSMode    ma
+       } else
+       {
+         mathjs_css = g_strdup(" ");
+-        mathjs_script = g_strdup_printf("<script src=\"file://%smathjax/MathJax.js?config=TeX-AMS_HTML\"></script>",
+-                                        SCRIPTS_DIR);
++        mathjs_script = g_strdup("<script src=\"file:///usr/share/mathjax/MathJax.js?config=TeX-AMS_HTML\"></script>");
+         mathjs_auto = g_strdup(" ");
+       }
+       break;

srcpkgs/Marker/template

@@ -1,12 +1,12 @@
 # Template file for 'Marker'
 pkgname=Marker
 version=2020.04.04
-revision=2
+revision=3
 build_style=meson
 hostmakedepends="glib-devel pkg-config itstool gettext"
 makedepends="gtksourceview-devel gtkspell3-devel gtk+3-devel libglib-devel
  webkit2gtk-devel"
-depends="iso-codes"
+depends="iso-codes mathjax2"
 short_desc="Gtk3 markdown editor"
 maintainer="Enno Boland <gottox@voidlinux.org>"
 license="GPL-3.0-or-later, ISC"