While we are drawing DrawString record, in most cases optional
StringFormat information is available.
If StringFromat information is available then we should use default
values.
For LeadingMargin for String the default value is 1/6 inch.

Change-Id: I4a0a68df5ebe74e810f8b5864232b477b3aac255
Reviewed-on: https://gerrit.libreoffice.org/62927
Tested-by: Jenkins
Reviewed-by: Bartosz Kosiorek <gang65@poczta.onet.pl>