MFV r351500: Fix CLEAR_HASH macro to be usable as a single statement.

MFC after:	2 weeks

sys/contrib/zlib/deflate.c

@@ -189,9 +189,11 @@ local const config configuration_table[10] = {
  * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
  * prev[] will be initialized on the fly.
  */
-#define CLEAR_HASH(s) do { \
-    s->head[s->hash_size-1] = NIL; \
-    zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head)); \
+#define CLEAR_HASH(s) \
+    do { \
+        s->head[s->hash_size-1] = NIL; \
+        zmemzero((Bytef *)s->head, \
+                 (unsigned)(s->hash_size-1)*sizeof(*s->head)); \
     } while (0)
 
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