Add a test for Read/Show of Data.Fixed

testsuite/tests/ghc-regress/lib/Data.Fixed/Makefile

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

testsuite/tests/ghc-regress/lib/Data.Fixed/all.T

+test('data-fixed-show-read', normal, compile_and_run, [''])

testsuite/tests/ghc-regress/lib/Data.Fixed/data-fixed-show-read.hs

+
+module Main (main) where
+
+import Data.Fixed
+
+main :: IO ()
+main = do doit 38.001
+          doit 38.009
+          doit 38.01
+          doit 38.09
+          print (read "38" :: Centi)
+          doit (-38.001)
+          doit (-38.009)
+          doit (-38.01)
+          doit (-38.09)
+          print (read "-38" :: Centi)
+
+doit :: Centi -> IO ()
+doit c = do let s = show c
+                r = read s :: Centi
+            putStrLn s
+            print r

testsuite/tests/ghc-regress/lib/Data.Fixed/data-fixed-show-read.stdout

+38.00
+38.00
+38.00
+38.00
+38.01
+38.01
+38.09
+38.09
+38.00
+-38.00
+-38.00
+-38.00
+-38.00
+-38.01
+-38.01
+-38.09
+-38.09
+-38.00