[Fix prevent issues]

[Fix prevent issues]
of screen_reader_vconf.c
 - CID 404741 Array compared against 0
 - CID 405344 Dereference null return value
 - CID 405972 Dereference null return value

of smart_notification.c
 - CID 398501 Resource leak

of structural_navi.c
 - CID 404103 Dereference null return value

of tests/atspi/atspi.c
 - CID 394796 Out-of-bounds read

of tests/smart_navi_suite.c
 - CID 387309 Dereference null return value

Change-Id: I2e333272e6580d6efa5c07a7e73ce7189dd1e2b8