x86: pass in pt_regs pointer for syscalls that need it

x86: pass in pt_regs pointer for syscalls that need it

Some syscalls need to access the pt_regs structure, either to copy
user register state or to modifiy it.  This patch adds stubs to load
the address of the pt_regs struct into the %eax register, and changes
the syscalls to regparm(1) to receive the pt_regs pointer as the
first argument.

Signed-off-by: Brian Gerst <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>