[dunecontrol] Improve path quoting in vcsetup command

Make sure to always quote paths that are relative to PREFIX_DIR, as that variable
may contain spaces.

bin/dunecontrol

@@ -364,14 +364,14 @@ run_default_vcsetup() {
         if [ ! -e "$GITHOOKPATH" ]; then
           # there is no hook yet, we can safely install ours
           echo "--> Installing Git pre-commit hook to enforce whitespace policy"
-          cp -p $PREFIX_DIR/bin/git-whitespace-hook "$GITHOOKPATH"
+          cp -p "$PREFIX_DIR/bin/git-whitespace-hook" "$GITHOOKPATH"
         else
           # there is already a hook, check whether it is our whitespace hook
           local HOOKTAG="$(eval head -n 2 \"$GITHOOKPATH\" | tail -n 1)"
           if [ "x$HOOKTAG" = "x# dune-git-whitespace-hook" ]; then
-            if [ $PREFIX_DIR/bin/git-whitespace-hook -nt "$GITHOOKPATH" ]; then
+            if [ "$PREFIX_DIR/bin/git-whitespace-hook" -nt "$GITHOOKPATH" ]; then
               echo "--> Updating Git pre-commit hook with newer version"
-              cp -p $PREFIX_DIR/bin/git-whitespace-hook "$GITHOOKPATH"
+              cp -p "$PREFIX_DIR/bin/git-whitespace-hook" "$GITHOOKPATH"
             fi
           else
             echo "WARNING: Existing pre-commit hook found!"