[FIX] Do not use chunked encoding with CGI/FastCGI
it's forbiden by http://tools.ietf.org/html/rfc3875#section-6.3.4

This correct bug 10001, https://bugzilla.xamarin.com/show_bug.cgi?id=10001

Signed-off-by: Etienne CHAMPETIER <etienne.champetier@fiducial.net>