Fix issue opening small v4 MAT files
Fix issue opening small v4 MAT files

* src/mat.c (Mat_Open): If 128 bytes was read, see if the file is a v5 or
      v7.3 file and if the mat version is not set, see if it is a v4 file

MaartenBent/matio,tbeu/matio,martinichka/matio-coder,tbeu/matio,tbeu/matio,CBL-ORION/matio-sf-mirror,tbeu/matio,martinichka/matio-coder,NJannasch/matio,MaartenBent/matio,NJannasch/matio,MaartenBent/matio,CBL-ORION/matio,CBL-ORION/matio-sf-mirror,MaartenBent/matio,CBL-ORION/matio,martinichka/matio-coder,telehan/libmatio,telehan/libmatio