compiler: introduce custom "GhcPrelude" Prelude

This switches the compiler/ component to get compiled with
-XNoImplicitPrelude and a `import GhcPrelude` is inserted in all
modules.

This is motivated by the upcoming "Prelude" re-export of
`Semigroup((<>))` which would cause lots of name clashes in every
modulewhich imports also `Outputable`

Reviewers: austin, goldfire, bgamari, alanz, simonmar

Reviewed By: bgamari

Subscribers: goldfire, rwbarton, thomie, mpickering, bgamari

Differential Revision: https://phabricator.haskell.org/D3989

1 files changed, 2 insertions, 0 deletions

diff --git a/compiler/codeGen/StgCmmCon.hs b/compiler/codeGen/StgCmmCon.hs
index 6438b8cd3c..1540d00715 100644
--- a/compiler/codeGen/StgCmmCon.hs
+++ b/compiler/codeGen/StgCmmCon.hs
@@ -17,6 +17,8 @@ module StgCmmCon (
 
 #include "HsVersions.h"
 
+import GhcPrelude
+
 import StgSyn
 import CoreSyn  ( AltCon(..) )