Adapt to google::protobuf::uint64 type change

Protobuf 3.5.2 redefines google::protobuf::uint64 from unsigned long
long to uint64_t, which is sometimes unsigned long and sometimes
unsigned long long.  Use PRIu64 to print it, and add an implementation
of ProtoOutputStream::write for long.

Bug: 117607748
Test: m checkbuild
Change-Id: I48912f58e2f63f4a98c3aefaa4f78cc2c719bb68