Import 'serde' crate version 1.0.115

Bug: 163175424
Test: N/A
Change-Id: Ibac4c3a38612d12add0cc5feaae8e190992a0386
diff --git a/src/private/mod.rs b/src/private/mod.rs
new file mode 100644
index 0000000..79e0a7d
--- /dev/null
+++ b/src/private/mod.rs
@@ -0,0 +1,4 @@
+mod macros;
+
+pub mod de;
+pub mod ser;