xbps-src: new pre-pkg hook that prints collected rdeps.

common/hooks/pre-pkg/999-collected-rdeps.sh

@@ -0,0 +1,7 @@
+# This hook displays resolved dependencies for a pkg.
+
+hook() {
+	if [ -e $PKGDESTDIR/rdeps ]; then
+		echo "   $(cat $PKGDESTDIR/rdeps)"
+	fi
+}