tools headers: Adopt verbatim copy of compiletime_assert() from kernel sources

# define __compiletime_error(message)

#endif

#ifdef __OPTIMIZE__

# define __compiletime_assert(condition, msg, prefix, suffix)		\

	do {								\

		extern void prefix ## suffix(void) __compiletime_error(msg); \

		if (!(condition))					\

			prefix ## suffix();				\

	} while (0)

#else

# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)

#endif

#define _compiletime_assert(condition, msg, prefix, suffix) \

	__compiletime_assert(condition, msg, prefix, suffix)

/**

 * compiletime_assert - break build and emit msg if condition is false

 * @condition: a compile-time constant condition to check

 * @msg:       a message to emit if condition is false

 *

 * In tradition of POSIX assert, this macro will break the build if the

 * supplied condition is *false*, emitting the supplied error message if the

 * compiler has support to do so.

 */

#define compiletime_assert(condition, msg) \

	_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)

/* Optimization barrier */

/* The "volatile" is due to gcc bugs */

#define barrier() __asm__ __volatile__("": : :"memory")