patch 8.1.0579: cannot attach properties to text

Problem:    Cannot attach properties to text.
Solution:   First part of adding text properties.
diff --git a/src/misc2.c b/src/misc2.c
index ce69597..87799b0 100644
--- a/src/misc2.c
+++ b/src/misc2.c
@@ -1191,6 +1191,9 @@
 # ifdef FEAT_CMDHIST
     init_history();
 # endif
+#ifdef FEAT_TEXT_PROP
+    clear_global_prop_types();
+#endif
 
 #ifdef FEAT_QUICKFIX
     {