delete surplus assignment

src/http/ngx_http_file_cache.c

diff --git a/src/http/ngx_http_file_cache.c b/src/http/ngx_http_file_cache.c
index 6fc823c..94ddbf6 100644
--- a/src/http/ngx_http_file_cache.c
+++ b/src/http/ngx_http_file_cache.c
@@ -368,8 +368,6 @@
     ngx_http_file_cache_t         *cache;
     ngx_http_file_cache_header_t  *h;
 
-    c = r->cache;
-
     n = ngx_http_file_cache_aio_read(r, c);
 
     if (n < 0) {