Remove the tests/lib/PrettyPrint tests; part of #1161

I'll send them to pretty upstream.

testsuite/tests/lib/PrettyPrint/Makefile

-TOP=../../..
-include $(TOP)/mk/boilerplate.mk
-include $(TOP)/mk/test.mk

testsuite/tests/lib/PrettyPrint/T3911.hs

-
-module Main where
-
-import Text.PrettyPrint.HughesPJ
-
-xs :: [Doc]
-xs = [text "hello",
-      nest 10 (text "world")]
-
-d1 :: Doc
-d1 = vcat xs
-
-d2 :: Doc
-d2 = foldr ($$) empty xs
-
-d3 :: Doc
-d3 = foldr ($+$) empty xs
-
-main :: IO ()
-main = do print d1
-          print d2
-          print d3
-

testsuite/tests/lib/PrettyPrint/T3911.stdout

-hello     world
-hello     world
-hello
-          world

testsuite/tests/lib/PrettyPrint/all.T

-test('pp1', compose(expect_broken(1062), only_ways(['normal'])), compile_and_run, [''])
-test('T3911', normal, compile_and_run, [''])

testsuite/tests/lib/PrettyPrint/pp1.hs

--- This code used to print an infinite string, by calling 'spaces'
--- with a negative argument.  There's a patch in the library now,
--- which makes 'spaces' do something sensible when called with a negative
--- argument, but it really should not happen at all.
-
-
-module Main where
-
-import Text.PrettyPrint.HughesPJ
-
-
-ncat x y = nest 4 $ cat [ x, y ]
-
-d1 = foldl1 ncat $ take 50 $ repeat $ char 'a'
-d2 = parens $  sep [ d1, text "+" , d1 ]
-
-main = print d2
-

testsuite/tests/lib/PrettyPrint/pp1.stdout

-This output is not what is expected, becuase the
-test "works" now, by virtue of a hack in HughesPJ.spaces.
-I'm leaving this strange output here to remind us to look
-at the root cause of the problem.  Sometime.
\ No newline at end of file