darwin/stdenv: tapi stub based bootstrap

Fixes bootstrapping on macOS Big Sur.

pkgs/stdenv/darwin/unpack-bootstrap-tools.sh

@@ -17,41 +17,6 @@ for i in $out/bin/*; do
   fi
 done
 
-install_name_tool \
-  -id $out/lib/system/libsystem_c.dylib \
-  $out/lib/system/libsystem_c.dylib
-
-install_name_tool \
-  -id $out/lib/system/libsystem_kernel.dylib \
-  $out/lib/system/libsystem_kernel.dylib
-
-# TODO: this logic basically duplicates similar logic in the Libsystem expression. Deduplicate them!
-libs=$(cat $reexportedLibrariesFile | grep -v '^#')
-
-for i in $libs; do
-  if [ "$i" != "/usr/lib/system/libsystem_kernel.dylib" ] && [ "$i" != "/usr/lib/system/libsystem_c.dylib" ]; then
-    args="$args -reexport_library $i"
-  fi
-done
-
-ld -macosx_version_min 10.7 \
-   -arch x86_64 \
-   -dylib \
-   -o $out/lib/libSystem.B.dylib \
-   -compatibility_version 1.0 \
-   -current_version 1226.10.1 \
-   -reexport_library $out/lib/system/libsystem_c.dylib \
-   -reexport_library $out/lib/system/libsystem_kernel.dylib \
-   $args
-
-ln -s libSystem.B.dylib $out/lib/libSystem.dylib
-
-for name in c dbm dl info m mx poll proc pthread rpcsvc util gcc_s.10.4 gcc_s.10.5; do
-  ln -s libSystem.dylib $out/lib/lib$name.dylib
-done
-
-ln -s libresolv.9.dylib $out/lib/libresolv.dylib
-
 for i in $out/lib/*.dylib $out/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation; do
   if test ! -L "$i" -a "$i" != "$out/lib/libSystem*.dylib"; then
     echo "Patching $i"