fix-build-using-unregisterized-v8.2

fix-build-using-unregisterized-v8.2

.
  error: conflicting types for 'ghc_GhcPrelude_zdtrModule4_bytes'
  note: in definition of macro 'EB_'
  #define EB_(X)    extern const char X[]
  note: previous definition of 'ghc_GhcPrelude_zdtrModule4_bytes' was here
  char ghc_GhcPrelude_zdtrModule4_bytes[] = "ghc";
.
 For more information about the problem, see https://phabricator.haskell.org/D4114.
.
 This patch is a rework of https://phabricator.haskell.org/D3741.
 It modifies Stg.h to include the old definitions, if a compiler older than
 8.4 is being used.
.
 This patch can be removed, once ghc-8.2 is no longer the bootstrap compiler.
Author: Ilias Tsitsimpis <iliastsi@debian.org>
Bug: https://ghc.haskell.org/trac/ghc/ticket/15201

Gbp-Pq: Name fix-build-using-unregisterized-v8.2