...so that running those tests with a read-only SRCDIR succeeds.  (Needed to
move sc/qa/uitest/calc_tests/data/tdf76731.ods to fit the changes made to
sc/UITest_statistics.mk; all documents used by that test need to be at the same
place.)

Change-Id: I5c4a28539b9bacde3ca8983502ceed8e4688c787
Reviewed-on: https://gerrit.libreoffice.org/68683
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>