patch 9.0.0128: Coverity complains about possible double free

Problem:    Coverity complains about possible double free.
Solution:   Clear the pointer to avoid warnings.
diff --git a/src/charset.c b/src/charset.c
index a8173c1..2b65747 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -912,16 +912,13 @@
 	char_u		*line,
 	char_u		*ptr)
 {
+    CLEAR_POINTER(cts);
     cts->cts_win = wp;
     cts->cts_lnum = lnum;
     cts->cts_vcol = col;
     cts->cts_line = line;
     cts->cts_ptr = ptr;
 #ifdef FEAT_PROP_POPUP
-    cts->cts_text_prop_count = 0;
-    cts->cts_has_prop_with_text = FALSE;
-    cts->cts_cur_text_width = 0;
-    cts->cts_with_trailing = 0;
     if (lnum > 0)
     {
 	char_u *prop_start;
@@ -951,7 +948,7 @@
 		if (!cts->cts_has_prop_with_text)
 		{
 		    // won't use the text properties, free them
-		    vim_free(cts->cts_text_props);
+		    VIM_CLEAR(cts->cts_text_props);
 		    cts->cts_text_prop_count = 0;
 		}
 	    }
@@ -969,8 +966,8 @@
 #ifdef FEAT_PROP_POPUP
     if (cts->cts_text_prop_count > 0)
     {
-	vim_free(cts->cts_text_props);
-	cts->cts_text_prop_count = 0;  // avoid double free
+	VIM_CLEAR(cts->cts_text_props);
+	cts->cts_text_prop_count = 0;
     }
 #endif
 }