Extract special BUILD file for //tools/cpp when present in the @bazel_tools

Progress towards https://github.com/bazelbuild/bazel/issues/10134.

RELNOTES: None.
PiperOrigin-RevId: 280654359
diff --git a/src/create_embedded_tools.py b/src/create_embedded_tools.py
index 78e6685..ccd19db 100644
--- a/src/create_embedded_tools.py
+++ b/src/create_embedded_tools.py
@@ -33,6 +33,7 @@
      lambda x: 'tools/build_defs/repo/BUILD'),
     ('*tools/platforms/BUILD.tools', lambda x: 'platforms/BUILD'),
     ('*tools/platforms/*', lambda x: 'platforms/' + os.path.basename(x)),
+    ('*tools/cpp/BUILD.tools', lambda x: 'tools/cpp/BUILD'),
     ('*tools/cpp/runfiles/generated_*',
      lambda x: 'tools/cpp/runfiles/' + os.path.basename(x)[len('generated_'):]),
     ('*jarjar_command_deploy.jar',