split_complex_* flaw

[David Edelsohn]

>>>>> Alan Modra writes:

Alan> This is where things go wrong.  va_list on powerpc64-linux is just
Alan> a simple pointer.  va_arg(ap, _Complex float) is looking for a pair
Alan> of adjacent floats in a doubleword, but as you say, the stack image
Alan> is two doublewords with the split_complex_* code.

	Either the default implementation of GCC's std_builtin_va_arg
machinery needs to do something special for SPLIT_COMPLEX_ARGS or each
port needs to do something special.

David