x86, asmlinkage, lguest: Fix C functions used by inline assembler

- Make the C code used by the paravirt stubs visible
- Since they have to be global now, give them a more unique
name.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1382458079-24450-3-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>