Fix bug in lat/sausages.cc whereby do_mbr_ was uninitialized (bad bug-- could...

Fix bug in lat/sausages.cc whereby do_mbr_ was uninitialized (bad bug-- could randomly not do MBR or do it).

git-svn-id: https://svn.code.sf.net/p/kaldi/code/trunk@2499 5e6a8d80-dfce-4ca6-a32a-6e07a63d50c8