UT_HOSTSIZE (/usr/include/utmp.h) is set to 16.  This is not possible
	to put IPv6 numeric address into ut_host[].
	IPv6 numeric is usually fit into 40 bytes, in worst case 46 bytes
	including "\0".  Worst case is like follows:
		1111:2222:3333:4444:5555:123.123.123.123

	Queestion: is it possible for us to raise UT_HOSTSIZE to 46, or 40?

	I suspect backward compatibility is the problem.  utmp files does not
	have no file format version number info in it, so old and new version
	of file cannot coexist.  Also, some of third-party application may
	hardcode UT_HOSTSIZE, and they may have trouble parsing utmp files.
	If UT_HOSTSIZE is decided in any of standards like POSIX
	I should try to change the definition in that document first.
	Let me know your opinions.

itojun