Add dummy tcb-offsets.h
* This file is used during creation of real tcb-offsets.h
because lowlevellock.h from i386 also include tcb-offsets.h
and it is inturn included by tls.h and tls.h is used in
the dummy C file generated from tcb-offsets.sym, it created
a catch-22
Signed-off-by: Khem Raj <raj.khem@gmail.com>