This patch enables the use of abstract debug registers in
process-handling routines, according to the new hardware breakpoint
Api.

[ Impact: adapt thread breakpoints handling code to the new breakpoint Api ]
Original-patch-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NK.Prasad <prasad@linux.vnet.ibm.com>
Reviewed-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>