use new C++ noreturn syntax
namespace vespalib {
-extern void hdr_abort(const char *message,
+[[noreturn]] extern void
+hdr_abort(const char *message,
const char *file,
- unsigned int line) __attribute__((__noreturn__));
+ unsigned int line);
#define HDR_ABORT(msg) \
(vespalib::hdr_abort(msg, __FILE__, __LINE__))
