Mark flaky fault-localization test as FUTURE

The test will sometimes pass, depending on what model the solver
produces. When such a passing model happens to be is produced, it breaks
our checking of "KNOWNBUG" tests.

Author: tautschnig

regression/cbmc/fault_localization-all_properties2/test.desc

@@ -1,4 +1,4 @@
-KNOWNBUG
+FUTURE
 main.c
 --localize-faults
 ^EXIT=10$
@@ -8,4 +8,6 @@ line 9 function main$
 --
 --
 CBMC wrongly reports line 7 as the faulty statement when instead it should be
-line 9.
+line 9. The test is marked as "FUTURE" as it will sometimes pass, depending on
+what model the solver produces. It would, therefore, break our checking of
+"KNOWNBUG" tests.