GHC 7.6.1 compatibility

- switch from ClockTime to UTCTime in Info.pprInfo
- make ghc-mod loggers always take a first argument of type DynFlags
- consolidate GHC API shims in Gap.hs--this depends on tracingDynFlags,
which is unfortunate

Check.hs

@@ -7,7 +7,7 @@ import ErrMsg
 import Exception
 import GHC
 import GHCApi
-import Prelude hiding (catch)
+import Prelude
 import Types
 
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