take MALLOC_OPTIONS=J into account in slab allocator

src/core/ngx_slab.c

diff --git a/src/core/ngx_slab.c b/src/core/ngx_slab.c
index 9f63a91..b187026 100644
--- a/src/core/ngx_slab.c
+++ b/src/core/ngx_slab.c
@@ -58,9 +58,22 @@
 
 
 #if (NGX_DEBUG_MALLOC)
-#define ngx_slab_junk(p, size)  ngx_memset(p, 0xD0, size)
+
+#define ngx_slab_junk(p, size)     ngx_memset(p, 0xD0, size)
+
 #else
+
+#if (NGX_FREEBSD)
+
+#define ngx_slab_junk(p, size)                                                \
+    if (ngx_freebsd_debug_malloc)  ngx_memset(p, 0xD0, size)
+
+#else
+
 #define ngx_slab_junk(p, size)
+
+#endif
+
 #endif
 
 static ngx_slab_page_t *ngx_slab_alloc_pages(ngx_slab_pool_t *pool,