fix segfault if upstream sends trailing ";" in "charset="

src/http/ngx_http_upstream.c

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 6f548a3..6af214c 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -2326,6 +2326,8 @@
 
         r->headers_out.charset.len = h->value.data + h->value.len - p;
         r->headers_out.charset.data = p;
+
+        return NGX_OK;
     }
 
     return NGX_OK;