eukleides: allow PostScript transparency

pkgs/applications/science/math/eukleides/default.nix

···
     sha256 = "0s8cyh75hdj89v6kpm3z24i48yzpkr8qf0cwxbs9ijxj1i38ki0q";
   };
 
-  # use $CC instead of hardcoded gcc
-  patches = [ ./use-CC.patch ];
+  patches = [
+    # use $CC instead of hardcoded gcc
+    ./use-CC.patch
+    # allow PostScript transparency in epstopdf call
+    ./gs-allowpstransparency.patch
+  ];
 
   nativeBuildInputs = [ bison flex texinfo makeWrapper ];
 

pkgs/applications/science/math/eukleides/gs-allowpstransparency.patch

···
+--- a/bash/euktopdf
++++ b/bash/euktopdf
+@@ -55,6 +55,6 @@ do
+     exit 1
+   fi
+   dvips -q -E -o $base.eps $base.dvi &&
+-  epstopdf $base.eps &&
++  epstopdf --gsopt=-dALLOWPSTRANSPARENCY $base.eps &&
+   rm -f $base.{tex,log,dvi,eps}
+ done