Fixed client buffer reallocation for HTTP/3. Preserving pointers within the client buffer is not needed for HTTP/3 because all data is either allocated from pool or static. Unlike with HTTP/1, data typically cannot be referenced directly within the client buffer. Trying to preserve NULLs or external pointers lead to broken pointers. Also, reverted changes in ngx_http_alloc_large_header_buffer() not relevant for HTTP/3 to minimize diff to mainstream.

--- a/src/http/v3/ngx_http_v3_request.c
+++ b/src/http/v3/ngx_http_v3_request.c
@@ -60,6 +60,7 @@ ngx_http_v3_parse_request(ngx_http_reque
 
         r->h3_parse = st;
         r->parse_start = b->pos;
+        r->state = 1;
     }
 
     while (b->pos < b->last) {