Adapt to google::protobuf::uint64 type change

Protobuf 3.9.1 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
Exempt-From-Owner-Approval: approved at https://android-review.googlesource.com/q/Ib2d3f4e17857f8ccbbe342ce6678e76b591df510
Change-Id: Ib2d3f4e17857f8ccbbe342ce6678e76b591df510