patch 8.1.2371: FEAT_TEXT_PROP is a confusing name

Problem:    FEAT_TEXT_PROP is a confusing name.
Solution:   Use FEAT_PROP_POPUP. (Naruhiko Nishino, closes #5291)
diff --git a/src/eval.c b/src/eval.c
index b65f29e..c37d6fd 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -3890,7 +3890,7 @@
     if (aucmd_win != NULL)
 	abort = abort || set_ref_in_item(&aucmd_win->w_winvar.di_tv, copyID,
 								  NULL, NULL);
-#ifdef FEAT_TEXT_PROP
+#ifdef FEAT_PROP_POPUP
     for (wp = first_popupwin; wp != NULL; wp = wp->w_next)
 	abort = abort || set_ref_in_item(&wp->w_winvar.di_tv, copyID,
 								  NULL, NULL);
@@ -3954,7 +3954,7 @@
     abort = abort || set_ref_in_term(copyID);
 #endif
 
-#ifdef FEAT_TEXT_PROP
+#ifdef FEAT_PROP_POPUP
     abort = abort || set_ref_in_popups(copyID);
 #endif