pv: fix minisetlocale related build failure

pv configure script is somewhat stupid: if it cannot find the host
gettext tool msgfmt, it concludes that gettext is not available, and
provides its own minimal version. Unfortunately, this minimal version
conflicts with the available target gettext. We fix this by ensuring
that host-gettext is built if gettext support is enabled, by adding it
to the dependencies.

Fixes:

  http://autobuild.buildroot.org/results/d30/d30db79190f2cf8953751d55a5d34644f60daec4/



Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>