Enhancement: Give error and solution if using make instead of gmake

[John W. Eaton]

On  4-Aug-2008, Ole Tange wrote:

| May I suggest that the banner text tells the user to use 'gmake'
| instead of 'make'?

I added a note saying that GNU Make is needed.

| Maybe a check if '$0 --version' returns 'GNU Make' and if not ask the
| user to use gmake instead.

I don't think this is a good solution as we have no control over what
is printed when GNU Make runs, and there might be derivatives which
don't print this information in the same format we expect.

jwe