patch 8.1.1582: cannot build with +textprop but without +timers

Problem:    Cannot build with +textprop but without +timers.
Solution:   Add #ifdef. (Ola Söder, closes #4574)
diff --git a/src/version.c b/src/version.c
index 042c9c1..2af2912 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1582,
+/**/
     1581,
 /**/
     1580,