gettext: build libintl unconditionally for uClibc/musl

gettext: build libintl unconditionally for uClibc/musl

Only the initial patches of the gettext series have been applied, and
a bisectability problem has arised: when BR2_SYSTEM_ENABLE_NLS is
disabled, which is the default, gettext no longer builds libintl.

However, since packages have not yet been updated to the new gettext
logic, they still try to link against libintl, because they rely on
BR2_NEEDS_GETTEXT/BR2_NEEDS_GETTEXT_IF_LOCALE, which are true.

So, as a temporary measure, we adjust the gettext package so that it
unconditionally builds libintl for uClibc/musl, even when NLS is
disabled. This commit will be reverted once all packages have been
fixed.

Fixes:

  http://autobuild.buildroot.net/results/a4cf71c34dcc5c750ea87a16014c2cb2d28cdebd/
  (elfutils)

  http://autobuild.buildroot.net/results/cb9ae18295b21b3f9399be6edd82273add375656/
  (linux-pam)

  http://autobuild.buildroot.net/results/4225e5dfb6bcf590d9c1068112472ee82bc87d6b/
  (alsa-utils)

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