Remove excess declarations from unistd.h for XPG3/XPG4 (bug 17665).

Remove excess declarations from unistd.h for XPG3/XPG4 (bug 17665).

For XPG3/XPG4 (defined __USE_XOPEN && !defined __USE_UNIX98), unistd.h
declares many functions that should only be declared for __USE_MISC
(none of them are in XPG3/XPG4): sethostname sethostid getdomainname
setdomainname vhangup revoke profil acct getusershell endusershell
setusershell daemon.  The whole block with the [__USE_MISC ||
(__USE_XOPEN && !__USE_UNIX98)] conditional contains only functions
that are not in XPG3/XPG4, so this patch simply changes the
conditional.

Tested for x86_64 (testsuite, and that installed stripped shared
libraries are unchanged by this patch).

	[BZ #17665]
	* posix/unistd.h [__USE_MISC || (__USE_XOPEN && !__USE_UNIX98)]:
	Change conditional to [__USE_MISC].