tcl.tclRequiresCheckHook: refer to tclsh by absolute path

Without this, tcl has to be put in nativeBuildInputs or the hook fails.

pkgs/development/interpreters/tcl/generic.nix

@@ -225,6 +225,7 @@ stdenv.mkDerivation (finalAttrs: {
           name = "tcl-requires-check-hook";
           substitutions = {
             tcl_hook = ./tcl-requires-check-hook.tcl;
+            tclsh = lib.getExe finalAttrs.finalPackage;
           };
           meta = {
             inherit (finalAttrs.meta) maintainers platforms;

pkgs/development/interpreters/tcl/tcl-requires-check-hook.sh

@@ -7,7 +7,7 @@ tclRequiresCheckPhase () {
     if [ -n "$tclRequiresCheck" ]; then
         export TCLLIBPATH="$out/lib $TCLLIBPATH" # Redundant if tcl-package-hook is also used
         # FIXME: For some reason the output gets swallowed unless we pipe it through cat‽
-        tclsh @tcl_hook@ 2>&1 | cat
+        @tclsh@ @tcl_hook@ 2>&1 | cat
     fi
 }