Merge branch 'PR/agetty-split' of https://github.com/karelzak/util-linux-work

Merge branch 'PR/agetty-split' of https://github.com/karelzak/util-linux-work

* 'PR/agetty-split' of https://github.com/karelzak/util-linux-work: (24 commits)
  agetty: guard conditional function declarations in header
  agetty: fix path_cxt leak in credential loading
  agetty: move fakehost to struct agetty_options
  agetty: make longopts[] static const
  agetty: move usage() and parse_args() before main()
  agetty: clean up includes in agetty.c
  agetty: add public domain header to all source files
  agetty: remove duplicate ISSUEDIR_EXT from agetty.c
  agetty: move login argv initialization to utils.c
  agetty: move username to struct agetty_options
  agetty: move parse_speeds() to utils.c
  agetty: move init_special_char() to utils.c
  agetty: move FIRST_SPEED to tty.c
  agetty: use bool for struct agetty_issue bitfields
  agetty: split out issue file functions to issuefile.c
  agetty: move struct issue and related defines to agetty.h
  agetty: split out terminal functions to tty.c
  agetty: split out speed table and baud code to tty.c
  agetty: move utility functions to utils.c
  agetty: split out credential loading to credentials.c
  ...