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/macros.h b/src/macros.h
index 72fc26a..ca7e4b5 100644
--- a/src/macros.h
+++ b/src/macros.h
@@ -339,7 +339,7 @@
 #define IS_USER_CMDIDX(idx) ((int)(idx) < 0)
 
 // Give an error in curwin is a popup window and evaluate to TRUE.
-#ifdef FEAT_TEXT_PROP
+#ifdef FEAT_PROP_POPUP
 # define ERROR_IF_POPUP_WINDOW error_if_popup_window()
 #else
 # define ERROR_IF_POPUP_WINDOW 0