ghostscript: fix install names on Darwin

Fixes #355377.

This should avoid the need to mess around with `install_name_tool`
entirely. This mirrors what is done by Homebrew[^1] and MacPorts[^2].

This should also make the changes in #355853 and #357951 unnecessary.

[^1]: https://github.com/Homebrew/homebrew-core/blob/5ca4f8ce766c69d49321fb7da1d297b8232f40cf/Formula/g/ghostscript.rb#L76
[^2]: https://github.com/macports/macports-ports/blob/d8a05520fa6a81fa5b0365068590aff184976b69/print/ghostscript/Portfile#L114

pkgs/by-name/gh/ghostscript/package.nix

@@ -96,6 +96,8 @@ stdenv.mkDerivation rec {
   ;
 
   preConfigure = ''
+    export DARWIN_LDFLAGS_SO_PREFIX=$out/lib/
+
     # https://ghostscript.com/doc/current/Make.htm
     export CCAUX=$CC_FOR_BUILD
     ${lib.optionalString cupsSupport ''export CUPSCONFIG="${cups.dev}/bin/cups-config"''}
@@ -140,14 +142,6 @@ stdenv.mkDerivation rec {
     ln -s "$fonts/share/fonts" "$out/share/ghostscript/fonts"
   '';
 
-  # dynamic library name only contains major version number, eg. '10'
-  dylib_version = lib.versions.major version;
-  preFixup = lib.optionalString stdenv.hostPlatform.isDarwin ''
-    for file in $out/bin/{gs,gsc,gsx}; do
-      install_name_tool -change libgs.$dylib_version.dylib $out/lib/libgs.$dylib_version.dylib $file
-    done
-  '';
-
   # validate dynamic linkage
   doInstallCheck = true;
   installCheckPhase = ''