Changed error message to be more appropriate in the imaginary
"open_file_cache max=0" case.

src/http/ngx_http_core_module.c

diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index a1b49d7..ba51910 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -4400,7 +4400,7 @@
         if (ngx_strncmp(value[i].data, "max=", 4) == 0) {
 
             max = ngx_atoi(value[i].data + 4, value[i].len - 4);
-            if (max == NGX_ERROR) {
+            if (max <= 0) {
                 goto failed;
             }