[RFA] top Makefile.in: all-m4 depends on all-texinfo

[DJ Delorie]

* Check the toplevel files in the gcc tree; try to keep them as
  in-sync as you can.

* FYI, Gcc has recently removed texinfo from their source tree.  Make
  sure m4 builds without a checked-out texinfo (i.e. pre-installed
  texinfo only), just in case.

* Changes to the gcc versions go to gcc-patches@gcc.gnu.org (if it's
  the same patch as this one, post the patch with "approved by dj,
  committed" there).

Otherwise, your change is OK.