target-i386: Update CPUID feature set for TCG

The CPUID features QEMU presented to the guest were not up-to-date
with QEMU's emulated feature set.
Add the missing bits of recent (and not so recent) additions to
QEMU's emulation engine.
For stability reasons only the user mode usable bits are exposed for
now, features like Monitor or CR8LEG are left out.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
