Add BUILD.third_party to rules_cc

Only to make //third_party a package

RELNOTES: None
PiperOrigin-RevId: 228316989
diff --git a/third_party/BUILD b/third_party/BUILD
new file mode 100644
index 0000000..ded53b6
--- /dev/null
+++ b/third_party/BUILD
@@ -0,0 +1 @@
+# Intentionally empty, only there to make //third_party a package.
\ No newline at end of file