sdk: symlink everything under lib/ when using local SDK (#3074)

We rely on the packaged zoneinfo zip in CRDB, found under
lib/time/zoneinfo.zip. When using the remote SDK macro, we untar the
entire archive into the sandbox. When pointing to a local SDK however,
we previously ignored everything under lib. It feels reasonable to also
symlink lib/ into the sandbox given they have valid symbols to build
against.

We needed this patch in order to build CRDB with local go installations.

+cc cockroachdb/cockroach#56178

go/private/sdk.bzl

@@ -219,7 +219,7 @@ def _remote_sdk(ctx, urls, strip_prefix, sha256):
         )
 
 def _local_sdk(ctx, path):
-    for entry in ["src", "pkg", "bin"]:
+    for entry in ["src", "pkg", "bin", "lib"]:
         ctx.symlink(path + "/" + entry, entry)
 
 def _sdk_build_file(ctx, platform):