libbinder: size checks for Parcel+IBinder

(the ones for Parcel are just improved)

These types are used in prebuilts, so it's useful to know the size
changes w/ having to wait for DOA devices.

Bug: 166282674
Test: build only (these are compile-time checks)
Change-Id: Ib6deda78a3f2bf537b3163ae7ea5a703b1c8e289
diff --git a/libs/binder/Parcel.cpp b/libs/binder/Parcel.cpp
index 98ca829..39d6a2e 100644
--- a/libs/binder/Parcel.cpp
+++ b/libs/binder/Parcel.cpp
@@ -78,7 +78,11 @@
 namespace android {
 
 // many things compile this into prebuilts on the stack
-static_assert(sizeof(Parcel) == 60 || sizeof(Parcel) == 120);
+#ifdef __LP64__
+static_assert(sizeof(Parcel) == 120);
+#else
+static_assert(sizeof(Parcel) == 60);
+#endif
 
 static std::atomic<size_t> gParcelGlobalAllocCount;
 static std::atomic<size_t> gParcelGlobalAllocSize;