close unused file descriptors

[sgerwk]

Without this, a cgi reading from stdin will block because it still has the
write end of the pipe open. This matters to cgi scripts using POST requests
with multipart/form-data, as the examples in pages/index.cgi and
pages/getfile.cgi (let me know if you want me to remove these two files from
the commit, they are just examples to demonstrate the problem).

[gereoffy]

thank you, it saved my life :)

[gereoffy]

2 more close were missing in the fork-parent process:

@@ -936,6 +936,8 @@
 					 * cgi_pipe_post is mapped to the stdin for the CGI application
 					 * and we pipe our POST data (if there is any) here.
 					 */
+					close(cgi_pipe_w[1]);
+					close(cgi_pipe_r[0]);
 					FILE * cgi_pipe = fdopen(cgi_pipe_w[0], "r");
 					FILE * cgi_pipe_post = fdopen(cgi_pipe_r[1], "w");

and the _waitthread mess is no longer required!