Implement utmpx.h

Spec link: https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/utmpx.h.html

It is not base POSIX but an XSI option. We probably want this to be able to reduce the patch needed for the current openssh recipe (see cookbook!592 (merged) & cookbook!609 (merged)).

Structure

• utmpx

Constants

• EMPTY
• BOOT_TIME
• OLD_TIME
• NEW_TIME
• USER_PROCESS
• INIT_PROCESS
• LOGIN_PROCESS
• DEAD_PROCESS

Functions

• endutxent
• getutxent
• getutxid
• getutxline
• pututxline
• setutxent