Bug#326725: apt is missing build-dep on sgmltools-lite

[Max Kellermann <max@duempel.org>]

Package: apt
Version: 0.6.40.1

apt requires sgmltools-lite to compile, but this build dependency is
missing.  Output from a failed build without sgmltools-lite:

[...]
Creating html for offline.sgml to ../build/docs/offline.html
nsgmls:/etc/sgml/catalog:193:8:E: cannot open
"/usr/share/sgml/stylesheet/dsssl/sgmltools/sgmltools.cat" (No such
file or directory)
nsgmls:/etc/sgml/catalog:193:8:E: cannot open
"/usr/share/sgml/stylesheet/dsssl/sgmltools/sgmltools.cat" (No such
file or directory)
nsgmls:/etc/sgml/catalog:193:8:E: cannot open
"/usr/share/sgml/stylesheet/dsssl/sgmltools/sgmltools.cat" (No such
file or directory)
nsgmls:/etc/sgml/catalog:193:8:E: cannot open
"/usr/share/sgml/stylesheet/dsssl/sgmltools/sgmltools.cat" (No such
file or directory)
nsgmls:/etc/sgml/catalog:193:8:E: cannot open
"/usr/share/sgml/stylesheet/dsssl/sgmltools/sgmltools.cat" (No such
file or directory)
nsgmls:/etc/sgml/catalog:193:8:E: cannot open
"/usr/share/sgml/stylesheet/dsssl/sgmltools/sgmltools.cat" (No such
file or directory)
nsgmls:/etc/sgml/catalog:193:8:E: cannot open
"/usr/share/sgml/stylesheet/dsssl/sgmltools/sgmltools.cat" (No such
file or directory)
nsgmls:/etc/sgml/catalog:193:8:E: cannot open
"/usr/share/sgml/stylesheet/dsssl/sgmltools/sgmltools.cat" (No such
file or directory)
make[2]: *** [../build/docs/dpkg-tech.html] Error 1
[...]