Suppress warnings when compiling primitive and random

And fix a redundant constraint warning in a test that requires
primitive.

mk/warnings.mk

@@ -79,6 +79,11 @@ libraries/pretty_dist-install_EXTRA_HC_OPTS += -Wno-unused-imports
 
 # primitive has a warning about deprecated use of GHC.IOBase
 libraries/primitive_dist-install_EXTRA_HC_OPTS += -Wno-unused-imports
+# primitive uses deprecated Control.Monad.Trans.Error
+libraries/primitive_dist-install_EXTRA_HC_OPTS += -Wno-deprecations
+
+# See https://github.com/haskell/random/pull/20
+libraries/random_dist-install_EXTRA_HC_OPTS += -Wno-redundant-constraints
 
 # temporarily turn off unused-imports warnings for terminfo
 libraries/terminfo_dist-boot_EXTRA_HC_OPTS += -fno-warn-unused-imports

testsuite/tests/deriving/should_compile/T8138.hs

@@ -22,7 +22,7 @@ mutableByteArrayFromList xs = do
     loop arr 0 xs
     return arr
   where
-    loop :: (Prim a) => MutableByteArray s -> Int -> [a] -> ST s ()
+    loop :: MutableByteArray s -> Int -> [a] -> ST s ()
     loop _ _ [] = return ()
 
     loop arr i (x : xs) = do