add compute remote uuid to compute state url

Otherwise, two different compute remotes that happen to take the same
input would use the same compute state url. Which seems wrong.

Command/AddComputed.hs

@@ -147,7 +147,7 @@ perform o r program = do
 		| otherwise = ingestwith $
 			ingestAdd' nullMeterUpdate (Just ld) (Just stateurlk)
 	  where
-	  	stateurl = Remote.Compute.computeStateUrl state outputfile
+	  	stateurl = Remote.Compute.computeStateUrl r state outputfile
 		stateurlk = fromUrl stateurl Nothing True
 		outputfile' = tmpdir </> outputfile
 		ld = LockedDown ldc $ KeySource

Remote/Compute.hs

@@ -257,9 +257,9 @@ parseComputeState k b =
 		in go c' rest
 
 {- A compute: url for a given output file of a computation. -}
-computeStateUrl :: ComputeState -> OsPath -> URLString
-computeStateUrl st p = 
-	"annex-compute:" ++ fromOsPath p ++ "?" 
+computeStateUrl :: Remote -> ComputeState -> OsPath -> URLString
+computeStateUrl r st p = 
+	"annex-compute:" ++ fromUUID (uuid r) ++ "/" ++ fromOsPath p ++ "?" 
 		++ decodeBS (formatComputeState' Nothing st')
   where
 	-- Omit computeOutputs, so this gives the same result whether