treewide: Don't use envHook anymore

This commits needs a MAJOR audit as I oftentimes just guessed which of
`$hostOffset`, `$targetOffset`, or a fixed offset should be used.

pkgs/development/libraries/qt-5/hooks/qtbase-setup-hook.sh

@@ -42,11 +42,7 @@ qtEnvHook() {
         propagatedUserEnvPkgs+=" $1"
     fi
 }
-if [ "$crossConfig" ]; then
-   crossEnvHooks+=(qtEnvHook)
-else
-   envHooks+=(qtEnvHook)
-fi
+envHostTargetHooks+=(qtEnvHook)
 
 postPatchMkspecs() {
     local bin="${!outputBin}"