CVE-2026-42946: fix buffer over-read and excessive memory allocation in
ngx_http_scgi_module and ngx_http_uwsgi_module when an upstream server
returns an unrecognized status line; reset r->state before falling back to
header parsing so the header parser no longer resumes from a status-line
state and reads through an uninitialized r->header_name_start, and reuse
r->header_name_start to backtrack the buffer position for status lines
split across reads