HTTP/2: avoid sending output queue if there's nothing to send. Particularly this fixes alerts on OS X and NetBSD systems when HTTP/2 is configured over plain TCP sockets. On these systems calling writev() with no data leads to EINVAL errors being logged as "writev() failed (22: Invalid argument) while processing HTTP/2 connection".

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.