Bug#743835: xlbiff: `nmh is not installed'

[積丹尼 Dan Jacobson]

# aptitude install xlbiff
The following NEW packages will be installed:
  liblockfile1{a} (D: nmh) (xlbiff D: nmh D: liblockfile1)  nmh{a} (D: xlbiff, 
S: exim4-base, R: nmh) (xlbiff D: nmh)  xlbiff

And then
$ xlbiff