Fixed handling of empty root. Previously, a configuration with "root" set to an empty string tried test a character at clcf->root.data[-1]. Additional test added to make sure this won't happen. Reported by Markus Linnala, see http://mailman.nginx.org/pipermail/nginx-devel/2015-August/007210.html.

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.