fix failure in handle_cgi_request() when the number of bytes read from stdin is exactly the number of bytes occupied by the response headers (mg_write(..., len = 0) is an illegal mg_write() call)
fix failure in handle_cgi_request() when the number of bytes read from stdin is exactly the number of bytes occupied by the response headers (mg_write(..., len = 0) is an illegal mg_write() call)

GerHobbelt/civet-webserver,GerHobbelt/civet-webserver,commshare/civet-webserver,GerHobbelt/civet-webserver,GerHobbelt/civet-webserver,commshare/civet-webserver,commshare/civet-webserver,GerHobbelt/civet-webserver,commshare/civet-webserver,GerHobbelt/civet-webserver,commshare/civet-webserver,commshare/civet-webserver,commshare/civet-webserver