* build-aux/xgettext.scm: Move setting of environment variables to shell
header.
(main): Use SOURCE_DATE_EPOCH as fallback for timestamp. This fixes running
from a tarball.
* Makefile.am (EXTRA_DIST): Add it.
Change-Id: Ic487587b22495868fd2a21545a13dc9e3458299c
* build-aux/xgettext.scm: New script.
* po/guix/Makevars (XGETTEXT): Set it.
(XGETTEXT_OPTIONS): Add --xgettext option to `real' xgettext.
* po/packages/Makevars (XGETTEXT): Set it.
(XGETTEXT_OPTIONS): Add --xgettext option to `real' xgettext.
Change-Id: I71b6b843970090f765f46ac346b92a346560e3f0