[PATCH] i386: Verify important CPUID bits in real mode

Check some CPUID bits that are needed for compiler generated early in boot.
When the system is still in real mode before changing the VESA BIOS mode
it is possible to still display an visible error message on the screen.

Similar to x86-64.

Includes cleanups from Eric Biederman

Signed-off-by: Andi Kleen <ak@suse.de>