pulseaudio: remove dependency on gettext

The dependency on gettext is only due to libglib2, not due to
pulseaudio itself.  It works fine without gettext if libglib2 is
not selected.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>