This commit implements the getprotoent() family of functions, including
getprotoent()
getprotobyname()
getprotobynumber()
setprotoent()
endprotoent()
This implementation is very similar to the getservent family of functions,
which is what led to the discovery of a bug in the process of reading the aliases.
The ByteBuffer for the alias strings didn't include a null terminating character,
this was fixed for both the protoent and servent family of functions by appending a
null character to the end of them before adding them to the alias lists.
ee5816b9c8