* libmisc/Makefile.am: Install serdbg.h, serdbgcnf.h,
termios_printk.h, termios_printk_cnf.h to $(includedir)/rtems.
* libmisc/serdbg/serdbg.c: Include <rtems/serdbg.h> instead of
<serdbg.h>.
* libmisc/serdbg/serdbgio.c: Include <rtems/serdbg.h> instead of
<serdbg.h>.
* libmisc/serdbg/termios_printk.c: Include <rtems/termios_printk.h>
instead of <termios_printk.h>.