HTTP/2: fixed header block size calculation.

src/http/v2/ngx_http_v2_filter_module.c

diff --git a/src/http/v2/ngx_http_v2_filter_module.c b/src/http/v2/ngx_http_v2_filter_module.c
index 17cfcd8..bcffd85 100644
--- a/src/http/v2/ngx_http_v2_filter_module.c
+++ b/src/http/v2/ngx_http_v2_filter_module.c
@@ -222,7 +222,7 @@
     }
 
     if (r->headers_out.content_type.len) {
-        len += NGX_HTTP_V2_INT_OCTETS + r->headers_out.content_type.len;
+        len += 1 + NGX_HTTP_V2_INT_OCTETS + r->headers_out.content_type.len;
 
         if (r->headers_out.content_type_len == r->headers_out.content_type.len
             && r->headers_out.charset.len)