Upstream: fixed logging level of upstream invalid header errors. In b87b7092cedb (nginx 1.21.1), logging level of "upstream sent invalid header" errors was accidentally changed to "info". This change restores the "error" level, which is a proper logging level for upstream-side errors.

make -f misc/GNUmakefile release

the required tools:
*) xsltproc to build CHANGES,
*) xslscript.pl ( http://hg.nginx.org/xslscript ) to build XSLTs
   from XSLScript sources.


make -f misc/GNUmakefile icons

the required tool:
*) netpbm to create Win32 icons from xpm sources.