Re-enable signum examples in {Int,FP}Ops

This bumps the `copilot` submodule to bring in GaloisInc/copilot-1#8, which
fixes how `copilot-c99` and `copilot-theorem` handle `signum`. With these
fixes, we can finally enable `signum` in the `IntOps` and `FPOps` examples.

Fixes #14.

Author: RyanGlScott

copilot-verifier/examples/Copilot/Verifier/Examples/FPOps.hs

@@ -19,8 +19,7 @@ mkSpecFor _ nameSuffix = do
       stream = extern (mkName "stream") Nothing
 
   triggerOp1 (mkName "abs") abs stream
-  -- Currently fails due to https://github.com/GaloisInc/copilot-verifier/issues/14
-  -- triggerOp1 (mkName "signum") signum stream
+  triggerOp1 (mkName "signum") signum stream
   triggerOp1 (mkName "recip") recip stream
   triggerOp1 (mkName "exp") exp stream
   triggerOp1 (mkName "sqrt") sqrt stream

copilot-verifier/examples/Copilot/Verifier/Examples/IntOps.hs

@@ -18,8 +18,7 @@ spec = do
   _ <- prop "shiftByBits" (forall (0 <= shiftBy && shiftBy < 16))
 
   triggerOp1 "abs" abs stream
-  -- Currently fails due to https://github.com/GaloisInc/copilot-verifier/issues/14
-  -- triggerOp1 "signum" signum stream
+  triggerOp1 "signum" signum stream
   triggerOp1 "bwNot" complement stream
 
   triggerOp2 "add" (+) stream stream