[Bug c++/60932] make stdatomic.h compatible with C++

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60932

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Sebastian Huber from comment #2)
> With FreeBSD and clang this works fine.

Not on my freebsd host:

$ clang++ -std=c++11 a.cc
In file included from a.cc:5:
/usr/include/stdatomic.h:187:17: error: unknown type name '_Bool'
typedef _Atomic(_Bool)                  atomic_bool;
                ^
/usr/include/stdatomic.h:187:26: error: C++ requires a type specifier for all
declarations
typedef _Atomic(_Bool)                  atomic_bool;
~~~~~~~                                 ^

[... and other similar errors]