Fix scope_x509_validate_signature() return value
Fix scope_x509_validate_signature() return value

scope_x509_validate_signature() was returning uninitialized stack data
on success and zero on failure.

cmusatyalab/opendiamond,cmusatyalab/opendiamond,cmusatyalab/opendiamond,cmusatyalab/opendiamond,cmusatyalab/opendiamond