patch 8.1.0579: cannot attach properties to text

Problem:    Cannot attach properties to text.
Solution:   First part of adding text properties.
diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index 5b85156..941cbd3 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -177,6 +177,7 @@
 	    test_terminal_fail.res \
 	    test_textformat.res \
 	    test_textobjects.res \
+	    test_textprop.res \
 	    test_undo.res \
 	    test_user_func.res \
 	    test_usercommands.res \