ignore: Generated .dat files from tests

Tests are run from toplevel's dir
and some .dat files are created from them,
and should not be commited,
while those along json files (not in project dir)
should be on changes, and they won't be ignored by this change.

Bug: https://jira.iotivity.org/browse/IOT-2599
Change-Id: I6c0cdde527889390661c14d0dc98dcced702c73d
Signed-off-by: Philippe Coval <philippe.coval@osg.samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/21995Tested-by: jenkins-iotivity <jenkins@iotivity.org>
Reviewed-by: George Nash <george.nash@intel.com>
Reviewed-by: Mats Wichmann <mats@linux.com>
Reviewed-by: Randeep Singh <randeep.s@samsung.com>

.gitignore

@@ -90,6 +90,7 @@ iotivity.pc
 tmp/
 *.tmp
 *.tmp.*
+/*.dat
 
 # Ignore GCov generated files
 *.gcda