1.0.30.3: deal with load-time-value constants more aggressively

1.0.30.3: deal with load-time-value constants more aggressively

* Revert 1.0.29.54.rc5 to allow constant moves from LTV TNs.

* Modify the relevant VOPs to handle LTV constants correctly.
  While this mostly results in duplicated code, VOPs can generate
  better code even for unknown values in the constant vector.