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/buffer.c b/src/buffer.c
index 4868428..4f38f91 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -861,7 +861,7 @@
 #ifdef FEAT_SYN_HL
     syntax_clear(&buf->b_s);	    // reset syntax info
 #endif
-#ifdef FEAT_TEXT_PROP
+#ifdef FEAT_PROP_POPUP
     clear_buf_prop_types(buf);
 #endif
     buf->b_flags &= ~BF_READERR;    // a read error is no longer relevant
@@ -5522,7 +5522,7 @@
 	if (bt_prompt(buf))
 	    return (char_u *)_("[Prompt]");
 #endif
-#ifdef FEAT_TEXT_PROP
+#ifdef FEAT_PROP_POPUP
 	if (bt_popup(buf))
 	    return (char_u *)_("[Popup]");
 #endif