illumos gate

At present, we do compile time assertions like this:

#define    CTASSERT(x)        _CTASSERT(x, __LINE__)
#define    _CTASSERT(x, y)        __CTASSERT(x, y)
#define    __CTASSERT(x, y) \
    typedef char __compile_time_assertion__ ## y [(x) ? 1 : -1] __unused

Which appeared with the OpenZFS crypto checksum support.

Unfortunately, this means that only the source line is used to provide uniqueness. One cannot have two assertions at the same line number in the same compilation unit, which includes any headers.