Don't list S3 as a remote type when built without S3 support.

Remote/S3real.hs

@@ -28,8 +28,8 @@ import Crypto
 import Annex.Content
 import Utility.Base64
 
-remote :: RemoteType
-remote = RemoteType {
+remote :: Maybe RemoteType
+remote = Just $ RemoteType {
 	typename = "S3",
 	enumerate = findSpecialRemotes "s3",
 	generate = gen,
@@ -58,7 +58,7 @@ gen' r u c cst =
 			hasKeyCheap = False,
 			config = c,
 			repo = r,
-			remotetype = remote
+			remotetype = fromJust remote
 		}
 
 s3Setup :: UUID -> RemoteConfig -> Annex RemoteConfig

Remote/S3stub.hs

@@ -1,13 +1,7 @@
 -- stub for when hS3 is not available
 module Remote.S3 (remote) where
 
-import Types.Remote
 import Types
 
-remote :: RemoteType
-remote = RemoteType {
-	typename = "S3",
-	enumerate = return [],
-	generate = error "S3 not enabled",
-	setup = error "S3 not enabled"
-}
+remote :: Maybe RemoteType
+remote = Nothing