shims: always replace `_Bool` with `bool` in C++
This generalises the path to always perform this substitution in C++
mode.  This should repair the build of libdispatch on android.
#endif
// FreeBSD only defines _Bool in C mode. In C++ mode _Bool is not being defined.
-#if defined(__cplusplus) && (defined(__FreeBSD__) || defined(_WIN32))
+#if defined(__cplusplus)
#define _Bool bool
#endif
#include <stdatomic.h>
