eo-cxx: Add second NULL sentinel to avoid buffer overrun by efl_check.h

efl_check.h assumes at least one element exists when checking
parallelization and accesses the second element of the array without
checking its size first. Adding a second NULL sentinel fixes the problem.

T8141
Differential Revision: https://phab.enlightenment.org/D9588

src/tests/eo_cxx/eo_cxx_suite.cc

@@ -7,6 +7,7 @@
 
 static const Efl_Test_Case etc[] = {
    { NULL, NULL }
+   , { NULL, NULL }
 };
 
 int