fix CPU hog in cache manager
patch by Maxim Dounin
diff --git a/src/http/ngx_http_file_cache.c b/src/http/ngx_http_file_cache.c
index 0d97e94..f26fcbc 100644
--- a/src/http/ngx_http_file_cache.c
+++ b/src/http/ngx_http_file_cache.c
@@ -1027,6 +1027,7 @@
 
         if (fcn->count == 0) {
             ngx_http_file_cache_delete(cache, q, name);
+            wait = 0;
 
         } else {
             if (--tries) {
@@ -1191,7 +1192,7 @@
     ngx_http_file_cache_t  *cache = data;
 
     off_t   size;
-    time_t  next;
+    time_t  next, wait;
 
     next = ngx_http_file_cache_expire(cache);
 
@@ -1212,7 +1213,11 @@
             return next;
         }
 
-        next = ngx_http_file_cache_forced_expire(cache);
+        wait = ngx_http_file_cache_forced_expire(cache);
+
+        if (wait > 0) {
+            return wait;
+        }
 
         if (ngx_http_file_cache_manager_sleep(cache) != NGX_OK) {
             return next;