texlive: Use ghostscriptX -> ghostscript_headless

The code and typical use case suggest that ghostscript is not used
graphically. Removing this dependency reduces the build closure of
many tools that use texlive for documentation.

If this needs to be reverted, please state the graphical use case
in a comment, so we don't make this mistake again.

pkgs/tools/typesetting/tex/texlive/default.nix

@@ -3,7 +3,7 @@
   - current html: https://nixos.org/nixpkgs/manual/#sec-language-texlive
 */
 { stdenv, lib, fetchurl, runCommand, writeText, buildEnv
-, callPackage, ghostscriptX, harfbuzz
+, callPackage, ghostscript_headless, harfbuzz
 , makeWrapper, python3, ruby, perl, gnused, gnugrep, coreutils
 , libfaketime
 , useFixedHashes ? true
@@ -12,7 +12,7 @@
 let
   # various binaries (compiled)
   bin = callPackage ./bin.nix {
-    ghostscript = ghostscriptX;
+    ghostscript = ghostscript_headless;
     harfbuzz = harfbuzz.override {
       withIcu = true; withGraphite2 = true;
     };
@@ -25,7 +25,7 @@ let
   combine = import ./combine.nix {
     inherit bin combinePkgs buildEnv lib makeWrapper writeText
       stdenv python3 ruby perl gnused gnugrep coreutils libfaketime;
-    ghostscript = ghostscriptX; # could be without X, probably, but we use X above
+    ghostscript = ghostscript_headless;
   };
 
   # the set of TeX Live packages, collections, and schemes; using upstream naming