As suggested by Junio and Johannes, change the name of the former
attribute specfile to export-subst to indicate its function rather
than purpose and to make clear that it is not applied to working tree
files.
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Junio C Hamano <gitster@pobox.com>