stack-hook: deduplicate better

No need to check for duplicates as it is now handled by setup.sh
deduplication. Also should use targetOffset here instead of hostOffset
because we are using stack-hook natively.

pkgs/development/haskell-modules/stack-hook.sh

@@ -1,11 +1,11 @@
 addStackArgs () {
-  if [ -d "$1/lib" ] && [[ "$STACK_IN_NIX_EXTRA_ARGS" != *"--extra-lib-dirs=$1/lib"* ]]; then
+  if [ -n "$(echo $1/lib/lib*)" ]; then
     STACK_IN_NIX_EXTRA_ARGS+=" --extra-lib-dirs=$1/lib"
   fi
 
-  if [ -d "$1/include" ] && [[ "$STACK_IN_NIX_EXTRA_ARGS" != *"--extra-include-dirs=$1/include"* ]]; then
+  if [ -d "$1/include" ]; then
     STACK_IN_NIX_EXTRA_ARGS+=" --extra-include-dirs=$1/include"
   fi
 }
 
-addEnvHooks "$hostOffset" addStackArgs
+addEnvHooks "$targetOffset" addStackArgs