Support optional features of MatIO on Windows and Mac
The Windows binary currently comes with a matio compiled without zlib and HDF5, which means that it cannot read/write compressed MAT files nor 7.3 MAT-files.
The Mac binary is in the same situation.
Fixing this would first require compiling static versions of zlib and HDF5 for the 2 platforms.
-lhdf5 -lz would have to be added to
LIBADD_MATIO or, better, we could use
pkg-config in ax_matio.m4 to detect the proper link flags (but the latter may be difficult in a cross-compiler environment).