wrong error message "`AM_INIT_AUTOMAKE' must be used"

[Bruno Haible]

Hi,

When attempting to use automake for the first time in a given old
project, I got an error message

   `AM_INIT_AUTOMAKE' must be used

so I added an AM_INIT_AUTOMAKE invocation to my configure.in. But
"automake lib/Makefile" kept saying

   `AM_INIT_AUTOMAKE' must be used

There are two possible causes of this error message:
  - If aclocal.m4 has not been regenerated.
  - If aclocal.m4 is not in the toplevel directory. (I had stored it in the
    AUX_DIR.)

So please update the error message to read something like

  no proper invocation of AM_INIT_AUTOMAKE was found.
  You should verify that configure.{in,ac} invokes AM_INIT_AUTOMAKE,
  that aclocal.m4 is present in the top level directory,
  and that aclocal.m4 was recently regenerated (using aclocal).

Bruno