fix warnings

src/http/modules/perl/nginx.xs

diff --git a/src/http/modules/perl/nginx.xs b/src/http/modules/perl/nginx.xs
index aef4c8b..035e261 100644
--- a/src/http/modules/perl/nginx.xs
+++ b/src/http/modules/perl/nginx.xs
@@ -467,7 +467,7 @@
     }
 
     if (header->key.len == sizeof("Content-Length") - 1
-        && ngx_strncasecmp(header->key.data, "Content-Length",
+        && ngx_strncasecmp(header->key.data, (u_char *) "Content-Length",
                            sizeof("Content-Length") - 1) == 0)
     {
         r->headers_out.content_length_n = (off_t) SvIV(value);
@@ -642,7 +642,7 @@
         XSRETURN_EMPTY;
     }
 
-    (void) ngx_cpystrn(path.data, filename, path.len + 1);
+    (void) ngx_cpystrn(path.data, (u_char *) filename, path.len + 1);
 
     clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);