Fix Bazel 8 crash when generating dsym or linkmap paths (#2651)

Fixes the crash described in
bazelbuild/bazel#24625 (comment)

apple/internal/linking_support.bzl

@@ -14,6 +14,10 @@
 
 """Support for linking related actions."""
 
+load(
+    "@bazel_skylib//lib:paths.bzl",
+    "paths",
+)
 load("@build_bazel_apple_support//lib:lipo.bzl", "lipo")
 load(
     "//apple/internal:cc_toolchain_info_support.bzl",
@@ -276,7 +280,7 @@ def _link_multi_arch_binary(
             else:
                 suffix = "_bin.dwarf"
             dsym_binary = ctx.actions.declare_shareable_artifact(
-                ctx.label.package + "/" + ctx.label.name + suffix,
+                paths.join(ctx.label.package, ctx.label.name + suffix),
                 child_config.bin_dir,
             )
             extensions["dsym_path"] = dsym_binary.path  # dsym symbol file
@@ -286,7 +290,7 @@ def _link_multi_arch_binary(
         linkmap = None
         if ctx.fragments.cpp.objc_generate_linkmap:
             linkmap = ctx.actions.declare_shareable_artifact(
-                ctx.label.package + "/" + ctx.label.name + ".linkmap",
+                paths.join(ctx.label.package, ctx.label.name + ".linkmap"),
                 child_config.bin_dir,
             )
             extensions["linkmap_exec_path"] = linkmap.path  # linkmap file