darwin.binutils: link unprefixed ld64 with prefix in binutils

ld64 is a cross-linker by default (albeit only to Darwin platforms), so
it is built without a prefix in the ld64 package. The linker in the
binutils package is expected to be prefixed, so adjust the build command
accordingly to make sure the linker is still linked correctly.

pkgs/os-specific/darwin/binutils/default.nix

···
     makeWrapper "${lib.getBin clang-unwrapped}/bin/clang" "$out/bin/${targetPrefix}as" \
       --add-flags "-x assembler -integrated-as -c"
 
-    ln -s '${lib.getBin ld64}/bin/${targetPrefix}ld' "$out/bin/${targetPrefix}ld"
+    ln -s '${lib.getBin ld64}/bin/ld' "$out/bin/${targetPrefix}ld"
     ${linkManPages (lib.getMan ld64) "ld" "ld"}
     ${linkManPages (lib.getMan ld64) "ld-classic" "ld-classic"}
     ${linkManPages (lib.getMan ld64) "ld64" "ld64"}