qemu/int128: Re-shuffle Int128Alias members

qemu/int128: Re-shuffle Int128Alias members

Clang 14, with --enable-tcg-interpreter errors with

include/qemu/int128.h:487:16: error: alignment of field 'i' (128 bits)
  does not match the alignment of the first field in transparent union;
  transparent_union attribute ignored [-Werror,-Wignored-attributes]
    __int128_t i;
               ^
include/qemu/int128.h:486:12: note: alignment of first field is 64 bits
    Int128 s;
           ^
1 error generated.

By placing the __uint128_t member first, this is avoided.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230501204625.277361-1-richard.henderson@linaro.org>