Build with large-file support on platforms where it matters Some hosts require you to define certain options to get a large off_t instead of a small one, to get useful ftell and fseek calls instead of ones that can only support 2GB files, and so on. This patch makes Libevent support those platforms by: * Defining the right options when we build, and * Changing our API so that it does not depend on the platform's definition of off_t. Based on discusion with Michael Herf