execute the php-cgi in the thttpd

 modify the libhttpd.c, add the next lines:

(void) my_snprintf(buf, sizeof(buf), "%s%s", hc->hs->cwd, strcmp( hc->origfilename, "." ) == 0 ? "" : hc->origfilename ); envp[envn++] = build_env("SCRIPT_FILENAME=%s", buf);

php-cgi need environment variable SCRIPT_FILENAME to execute the script with the absolute name. php-cgi will print "No input file specified" if it did not find the environment variable SCRIPT_FILENAME or the file name is not absolute.