Build fix: update bioformats submodule pointer

Should fix this breaking build:

http://hudson.openmicroscopy.org.uk/job/OMERO-trunk/3167/

...which was a result of my having merge #524 without checking that the submodule pointer was fine after https://github.com/openmicroscopy/bioformats/pull/233 was merged.  I was mistakenly thinking that since the merge builds passed, #524 could go in as-is without a problem.