HTTP/3: fixed handling of zero-length literal field line.

Previously, st->value was passed with NULL data pointer to header handlers.

Author: pluknet

src/http/v3/ngx_http_v3_parse.c

@@ -810,6 +810,7 @@ ngx_http_v3_parse_field_lri(ngx_connection_t *c,
 
             st->literal.length = st->pint.value;
             if (st->literal.length == 0) {
+                st->value.data = (u_char *) "";
                 goto done;
             }
 
@@ -932,6 +933,7 @@ ngx_http_v3_parse_field_l(ngx_connection_t *c,
 
             st->literal.length = st->pint.value;
             if (st->literal.length == 0) {
+                st->value.data = (u_char *) "";
                 goto done;
             }
 
@@ -1072,6 +1074,7 @@ ngx_http_v3_parse_field_lpbi(ngx_connection_t *c,
 
             st->literal.length = st->pint.value;
             if (st->literal.length == 0) {
+                st->value.data = (u_char *) "";
                 goto done;
             }