PackageTests/TestSuiteTests/ExeV10: Have large output

The test case is changed to print a rather large amount of text, large
enough to fill a buffer. This way, the buffer draining functionality in
the test runner is tested, and it reveals haskell#2398.

This makes the test suite currently fail, of course, but the bug was
there before.

Cabal/tests/PackageTests/TestSuiteTests/ExeV10/tests/test-Foo.hs

@@ -2,7 +2,11 @@ module Main where
 
 import Foo
 import System.Exit
+import Control.Monad
 
 main :: IO ()
-main | fooTest [] = exitSuccess
+main | fooTest [] = do
+        -- Make sure that the output buffer is drained
+        replicateM 10000 $ putStrLn "The quick brown fox jumps over the lazy dog"
+        exitSuccess
      | otherwise = exitFailure