reify requires mtl

testsuite/tests/ghc-regress/lib/Generics/reify/test.T

 setTestOpts(only_compiler_types(['ghc']))
 
 test( 'reify',
-      skip_if_fast,
+      compose(skip_if_fast, reqlib('mtl')),
       multimod_compile_and_run,
       ['Main','']
     )