pypy: remove explicit darwin minimum SDK (#471446)

diff --git a/rpython/translator/platform/darwin.py b/rpython/translator/platform/darwin.py

index 8c824a8459..f407fb6c07 100644

--- a/rpython/translator/platform/darwin.py

+++ b/rpython/translator/platform/darwin.py

@@ -26,12 +26,12 @@ class Darwin(posix.BasePosix):

     standalone_only = ('-mdynamic-no-pic',)

     shared_only = ()

-    link_flags = (DARWIN_VERSION_MIN,)

+    link_flags = ()

     cflags = ('-O3',

               '-fomit-frame-pointer',

               # The parser turns 'const char *const *includes' into 'const const char **includes'

               '-Wno-duplicate-decl-specifier',

-              DARWIN_VERSION_MIN,)

+              )

     so_ext = 'dylib'

     DEFAULT_CC = 'clang'

      inherit (sqlite) out dev;

      libsqlite = "${sqlite.out}/lib/libsqlite3${stdenv.hostPlatform.extensions.sharedLibrary}";

    })

    # PyPy sets an explicit minimum SDK version for darwin that is much older

    # than what we default to on nixpkgs.

    # Simply removing the explicit flag makes it use our default instead.

    ./darwin_version_min.patch

  ];

  postPatch = ''