fdo#68849: Add header guards to all include files

Added header guards to files in directory sw/

Change-Id: I5859f986c6f954d41a7940dc9ae8febaa714d34f
Reviewed-on: https://gerrit.libreoffice.org/9587
Reviewed-by: Thomas Arnhold <thomas@arnhold.org>
Tested-by: Thomas Arnhold <thomas@arnhold.org>