support alignment ops when processing statements in RegisterUse

For some reason we were very conservative in our support or abstract
operations over the processor state in the `RegisterUse` analysis.

In particular, we were failing to process code such as:

r23 := (bv_and r21 (0xfffffffffffffff0 :: [64]))

whose goal is to align the value in r21 at a 16-byte boundary.

This resulted in us failing to analyze some code that was realigning its
stack pointer.  With this change, the same code succeeds at propagating
the abstract stack pointer offset forward.

base/src/Data/Macaw/Analysis/RegisterUse.hs

@@ -71,6 +71,7 @@ import           Control.Monad (unless, when, zipWithM_)
 import           Control.Monad.Except (MonadError(..), Except)
 import           Control.Monad.Reader (MonadReader(..), ReaderT(..), asks)
 import           Control.Monad.State.Strict (MonadState(..), State, StateT, execStateT, evalState, gets, modify)
+import qualified Data.Bits as Bits
 import qualified Data.ByteString.Char8 as BSC
 import qualified Data.ByteString as BS
 import           Data.Foldable
@@ -678,6 +679,8 @@ processApp aid app = do
       setAssignVal aid (FrameExpr (o+fromInteger c))
     BVSub _ (FrameExpr o) (IVCValue (BVCValue _ c)) ->
       setAssignVal aid (FrameExpr (o-fromInteger c))
+    BVAnd _ (FrameExpr o) (IVCValue (BVCValue _ c)) ->
+      setAssignVal aid (FrameExpr (o Bits..&. memInt (fromInteger c)))
     appExpr -> do
       c <- gets sisAppCache
       -- Check to see if we have seen an app equivalent to