ghc: fix dylib load command limits in compiler version 8.x

See https://phabricator.haskell.org/D4714 for the full details.
This will be part of ghc 8.6.

Closes https://github.com/NixOS/nixpkgs/pull/40877.

pkgs/development/compilers/ghc/backport-dylib-command-size-limit.patch

@@ -0,0 +1,24 @@
+diff --git a/compiler/main/DriverPipeline.hs b/compiler/main/DriverPipeline.hs
+index acd0d61..3e83c15 100644
+--- a/compiler/main/DriverPipeline.hs
++++ b/compiler/main/DriverPipeline.hs
+@@ -1916,6 +1916,7 @@ linkBinary' staticLink dflags o_files dep_packages = do
+                       ++ pkg_framework_opts
+                       ++ debug_opts
+                       ++ thread_opts
++                      ++ (if (platformOS platform `elem` [OSDarwin]) then [ "-Wl,-dead_strip_dylibs" ] else [])
+                     ))
+ 
+ exeFileName :: Bool -> DynFlags -> FilePath
+diff --git a/compiler/main/SysTools.hs b/compiler/main/SysTools.hs
+index 1ab5b13..2ebbf51 100644
+--- a/compiler/main/SysTools.hs
++++ b/compiler/main/SysTools.hs
+@@ -1737,6 +1737,7 @@ linkDynLib dflags0 o_files dep_packages
+                  ++ map Option pkg_lib_path_opts
+                  ++ map Option pkg_link_opts
+                  ++ map Option pkg_framework_opts
++                 ++ [ Option "-Wl,-dead_strip_dylibs" ]
+               )
+         OSiOS -> throwGhcExceptionIO (ProgramError "dynamic libraries are not supported on iOS target")
+         _ -> do