GMP bootstrap fails with Autoconf 2.69d

[Paul Eggert]

On 11/16/20 2:41 AM, Vincent Lefevre wrote:
> URLs can contain commas (this occurs in practice, but
> perhaps not for BTS URLs), so that if commas or other characters
> are forbidden, this should be documented so that the URL is
> written with such characters encoded.

That was done in a patch by Zack Weinberg installed into Autoconf master about 
an hour ago. See:

https://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=3b8f293ec21062c55fe2835be6c8af7d58dfe0af

This patch should appear in Autoconf 2.70. However, something like the trivial 
patch I proposed to GMP configure.ac in 
<https://gmplib.org/list-archives/gmp-bugs/2020-November/004947.html> is still 
needed, as current GMP does not conform even to the revised Autoconf documentation.