[PATCH] configure.ac: drop unnecessary gnu99 extension checks

[Mark Wielaard]

Hi Adrian,

On Tue, Aug 10, 2021 at 03:56:51PM +0300, Adrian Ratiu via Elfutils-devel wrote:
> So in the interest of enabling Clang builds we remove the only
> remaining blocker: the configure checks for nested functions and
> variable length arrays which are also unused.

Can we just remove the whole configure test? And change the AC_PROG_CC
to AC_PROG_CC_C99?

The patch doesn't update the comments about what is being tested, and
the only thing being tested now is Mixed Declarations and Code, which
is a standard part of C99.

Have you tried running make check with an alternative compiler? There
are a couple of "self tests" which run the code on the just produced
binaries and it would be interesting to know whether or not all tests
pass.

Thanks,

Mark