Fix hTryLock in newer Haskell (OFD locks on Linux); fix imports

Author: michalrus

cardano-launcher/src/Cardano/Shell/Application.hs

@@ -63,7 +63,7 @@ checkIfApplicationIsRunning lockFilePath = do
     when (not fileExist) $
         writeFile lockFilePath ""
 
-    lockfileHandle      <- openFile lockFilePath ReadMode
+    lockfileHandle      <- openFile lockFilePath ReadWriteMode
     isAlreadyRunning    <- hTryLock lockfileHandle ExclusiveLock
 
     -- We need to inform the user if the application version is already running.

cardano-launcher/src/Cardano/Shell/Launcher.hs

@@ -29,7 +29,7 @@ module Cardano.Shell.Launcher
 import           Cardano.Prelude hiding (onException)
 
 import           Prelude (Show (..))
-import           Data.Aeson (FromJSON, ToJSON(toJSON), genericParseJSON, genericToJSON, defaultOptions)
+import           Data.Aeson (genericParseJSON, genericToJSON, defaultOptions)
 import           Data.Yaml as Y
 import qualified System.Process as Process
 import           Turtle (system)