patch 8.2.0526: Gcc 9 complains about empty statement

Problem:    Gcc 9 complains about empty statement.
Solution:   Add {}. (Dominique Pelle, closes #5894)

src/evalfunc.c

@@ -4561,7 +4561,9 @@ f_has(typval_T *argvars, typval_T *rettv)
     if (x == TRUE && n == FALSE)
     {
 	if (0)
-	    ;
+	{
+	    // intentionally empty
+	}
 #if defined(FEAT_BEVAL) && defined(FEAT_GUI_MSWIN)
 	else if (STRICMP(name, "balloon_multiline") == 0)
 	    n = multiline_balloon_available();

src/version.c

@@ -738,6 +738,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    526,
 /**/
     525,
 /**/