This checkbox was introduced in the commit
9a857437
This patch makes Calc persistently remember the option's setting between
invocations of the Find & Replace dialog.

Change-Id: I82c1355e85cd16ce13229d495a6d243e185318ad
Reviewed-on: https://gerrit.libreoffice.org/19574Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>