dos2unix: needs host-gettext

dos2unix uses xgettext to generate its .pot file.

Fixes:
http://autobuild.buildroot.net/results/eda/eda7eeb2fdf7a22c299858ac99d1b1953b15575e/
http://autobuild.buildroot.net/results/aaf/aaf2b77f964eb6259e2e4b1d5a13838c3a1eef21/
http://autobuild.buildroot.net/results/922/92289b63ebdf133ab910f058ffca8ba34e574208/



Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>