IPv4 addresses will be converted as v4-mapped-v6 address while
writting it to byte form. v4-mapped-v6 addresses in byte form will be
parsed to Inet4Address while converting it back.
Bug: 392509494
Test: atest NetworkStaticLibTests:com.android.net.moduletests.util.StructTest
Flag: EXEMPT refactor
Change-Id: Ia906d2cae7bb7402ff937da267c2552431b2d0f7