wrap-gapps-hook: also wrap symlinks to executables

Some programs store the executable in a different place and link it
from the `bin` directory. For example, Polari links `$out/bin/polari`
to `$out/share/polari/org.gnome.Polari`. `wrapGAppsHook` did not follow
symlinks so it was not able to wrap Polari, making it unable to access
GObject introspection definitions required for running the program.

I made the wrapping script follow symlinks to fix this corner case.

pkgs/build-support/setup-hooks/wrap-gapps-hook.sh

@@ -39,7 +39,7 @@ wrapGAppsHook() {
     targetDirs=( "${prefix}/bin" "${prefix}/libexec" )
     for targetDir in "${targetDirs[@]}"; do
       if [[ -d "${targetDir}" ]]; then
-        find "${targetDir}" -type f -executable -print0 \
+        find -L "${targetDir}" -type f -executable -print0 \
           | while IFS= read -r -d '' file; do
           echo "Wrapping program ${file}"
           wrapProgram "${file}" "${gappsWrapperArgs[@]}"