[Bug c/65467] [libgomp] sorry, unimplemented: '_Atomic' with OpenMP

["jeff.science at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65467

--- Comment #4 from Jeff Hammond <jeff.science at gmail dot com> ---
Apparently, the GCC team wants to make it impossible for anyone to build
software where independent components that share CFLAGS in the build system
cannot use both the C11 atomics header and the OpenMP flag.  It doesn't matter
if you use either feature, literally including stdatomic.h and compiling with
-fopenmp is impossible.

So projects that use autotools and support CFLAGS=-fopenmp now need to
segregate the build system to compile any source files that include stdatomic.h
using a different set of options from the default?

It is really hard to imagine how someone came to the conclusion this was a
reasonable thing to do.

Anyways, here is the trivial test program that is broken by CFLAGS=-fopenmp.

#include <stdatomic.h>

int main(void)
{
    return 0;
}