Added header guards to files in directories sal/, sal/, and scripting/

Change-Id: Ieb7f224f2d27bd671618c516f47f5b7f08c1d294
Reviewed-on: https://gerrit.libreoffice.org/9582Reviewed-by: Thomas Arnhold <thomas@arnhold.org>
Tested-by: Thomas Arnhold <thomas@arnhold.org>