patch 9.1.1225: extra NULL check in VIM_CLEAR()

Problem:  extra NULL check in VIM_CLEAR()
Solution: remove the NULL check and rely on the NULL check in vim_free()
          instead (Hirohito Higashi).

closes: #16936

Signed-off-by: Hirohito Higashi <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/macros.h b/src/macros.h
index 86ae33b..6c2931a 100644
--- a/src/macros.h
+++ b/src/macros.h
@@ -360,11 +360,8 @@
  */
 #define VIM_CLEAR(p) \
     do { \
-	if ((p) != NULL) \
-	{ \
-	    vim_free(p); \
-	    (p) = NULL; \
-	} \
+	vim_free(p); \
+	(p) = NULL; \
     } while (0)
 
 /*