add includes

src/core/ngx_crc.h

diff --git a/src/core/ngx_crc.h b/src/core/ngx_crc.h
index 11bf328..c77f037 100644
--- a/src/core/ngx_crc.h
+++ b/src/core/ngx_crc.h
@@ -8,6 +8,10 @@
 #define _NGX_CRC_H_INCLUDED_
 
 
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+
 /* 32-bit crc16 */
 
 static ngx_inline uint32_t