i18n: treat "make pot" as an explicitly-invoked target

po/git.pot is normally used as-is and not regenerated by people building git, so it is okay if an explicit "make po/git.pot" always automatically regenerates it. Depend on the magic FORCE target instead of explicitly keeping track of dependencies. This simplifies the makefile, in particular preparing for a moment when $(LIB_H), which is part of $(LOCALIZED_C), can be computed on the fly. It also fixes a slight breakage in which changes to perl and shell scripts did not trigger a rebuild of po/git.pot. We still need a dependency on GENERATED_H, to force those files to be built when regenerating git.pot. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>