Fixes a regression reproducible on CPUs without XSAVE support introduced
by 419abd49.

The regression commit erroneously assumes that if XSAVE is not supported
then the host signal context won't have xsave data set up.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=50271Signed-off-by: Paul Gofman <pgofman@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>