Fix the build against mdbtools 0.9.1

[Alexey Dokuchaev]

Hi there,

As of mdbtools v0.9.1, public API had been changed which affected recutils
build.  I've attempted to fix it by crafting naive patch* which may or may
not be 100% correct, it's just FYI.  I'd happily switch to official patch
or update to the next recutils release which would include the fix.

./danfe

*) 
https://svnweb.freebsd.org/ports/head/databases/recutils/files/patch-utils_mdb2rec.c