target/i386: Add {hw,sw}_reserved to X86LegacyXSaveArea

This completes the 512 byte structure, allowing the union to
be removed.  Assert that the structure layout is as expected.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
1 file changed