Merge pull request #222886 from wegank/gnustep-builder

gnustep: allow overriding preConfigure in gsmakeDerivation

pkgs/desktops/gnustep/make/builder.sh

···
 if [ -e .attrs.sh ]; then source .attrs.sh; fi
 source $stdenv/setup
 
+providedPreConfigure="$preConfigure";
+
 preConfigure() {
+    eval "$providedPreConfigure"
+
     . $GNUSTEP_MAKEFILES/GNUstep.sh
 }