[FIX][v2] Do not use chunked encoding with CGI/FastCGI

Hi

make run-test PROFILE=net_2_0 OK
make run-test PROFILE=net_4_0 OK
make run-test PROFILE=net_4_5 OK

make run-test PROFILE=net_3_5 don't run on my box with unrelated errors
http://pastebin.com/0EwAf3um

https://bugzilla.xamarin.com/show_bug.cgi?id=10001