Fix unwanted globbing of sed script

Fix unwanted globbing of sed script

Problem reported by mirabilos via Eric Blake in:
https://www.austingroupbugs.net/view.php?id=1558
https://lists.gnu.org/r/bug-autoconf/2022-02/msg00003.html
* lib/m4sugar/m4sh.m4 (_AS_TR_SH_PREPARE):
Define as_sed_sh as the sed script.  All uses of as_tr_sh changed.
Define as_tr_sh as before, but only for compatibility with scripts
that mistakenly use as_tr_sh directly.
(AS_TR_CPP_PREPARE): Likewise for as_sed_cpp and as_tr_cpp.