drx_insert_counter_update does not work with drreg

[zhaoqin]

Before we add drreg, we add utility functions like drx_insert_counter_update to allow clients instrument counter update code easily. However such functions performs its own aflags analysis and request user to provide TLS slots for register stealing, so it does not work with the drreg.
It would be nice if we can update those functions in a way so it could work with drreg.