(ah the joys of student access machines).
* much better support for cross compiling
* straighten out ANSI-conforming compiler checks
* avoid harmless compiler warnings reported by -Wcast-align
* fixed some sign extension problems on rather exotic machines where
sizeof(size_t) < sizeof(ptrdiff_t) and sizeof(lzo_uint) == sizeof(size_t)
* updated the configure system to use the latest Autoconf, Automake
and Libtool versions
