x86 setup: print missing CPU features in cleartext

Instead of obscure numbers, print the list of missing CPU features in
cleartext.  To conserve space, use a host program (mkcpustr.c) to
produce a compact list of mandatory features only.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>