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/move.c b/src/move.c
index b010ef9..8e53d8b 100644
--- a/src/move.c
+++ b/src/move.c
@@ -1181,7 +1181,7 @@
     curwin->w_valid |= VALID_WCOL|VALID_WROW|VALID_VIRTCOL;
 }
 
-#if (defined(FEAT_EVAL) || defined(FEAT_TEXT_PROP)) || defined(PROTO)
+#if (defined(FEAT_EVAL) || defined(FEAT_PROP_POPUP)) || defined(PROTO)
 /*
  * Compute the screen position of text character at "pos" in window "wp"
  * The resulting values are one-based, zero when character is not visible.