File fix-unregisterised-v8.4-8.6.patch of Package ghc

Index: ghc-8.10.0.20200123/includes/stg/MiscClosures.h
===================================================================
--- ghc-8.10.0.20200123.orig/includes/stg/MiscClosures.h
+++ ghc-8.10.0.20200123/includes/stg/MiscClosures.h
@@ -401,8 +401,12 @@ RTS_FUN_DECL(stg_copySmallMutableArrayzh
 RTS_FUN_DECL(stg_casSmallArrayzh);
 
 RTS_FUN_DECL(stg_newMutVarzh);
+#if __GLASGOW_HASKELL__ < 808
+RTS_FUN_DECL(stg_atomicModifyMutVarzh);
+#else
 RTS_FUN_DECL(stg_atomicModifyMutVar2zh);
 RTS_FUN_DECL(stg_atomicModifyMutVarzuzh);
+#endif
 RTS_FUN_DECL(stg_casMutVarzh);
 
 RTS_FUN_DECL(stg_isEmptyMVarzh);