repeated assignments without using the value (unit test edition)

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cppcheck messages:
{{{
src/tests/mutex-test/mutex-test.c:47: performance: Variable 'status' is reassigned a value before the old one has been used.
src/tests/mutex-test/mutex-test.c:100: performance: Variable 'status' is reassigned a value before the old one has been used.
src/tests/mutex-test/mutex-test.c:154: performance: Variable 'status' is reassigned a value before the old one has been used.
src/unit-tests/oscore-test/ut_oscore_task_test.c:205: performance: Variable 'res' is reassigned a value before the old one has been used.
src/unit-tests/oscore-test/ut_oscore_task_test.c:508: performance: Variable 'res' is reassigned a value before the old one has been used.
src/unit-tests/oscore-test/ut_oscore_task_test.c:522: performance: Variable 'res' is reassigned a value before the old one has been used.
src/unit-tests/oscore-test/ut_oscore_task_test.c:594: performance: Variable 'res' is reassigned a value before the old one has been used.
(484 more lines...)
}}}

There are two lines indicating sources outside testing, a separate bug
has been filed as we may put more priority on fixing those lines than
on globally smashing this bug in the test code.

Recommended fix methods, PICK ONE:

1. Actually check the status variables to see if an error was returned
2. put a (void) cast on the function call instead of storing the data that is not actually ever going to be looked at. This advertises to maintainers and to the compiler and to static analysis that we are purposefully ignoring the return value of the function.

[skliper]

Imported from trac issue 134. Created by glimes on 2015-12-10T14:51:26, last modified: 2019-08-14T14:11:46

[skliper]

Trac comment by glimes on 2015-12-10 14:52:22:

See ticket #158 for this warning outside unit test code.

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Trac comment by glimes on 2015-12-31 13:00:35:

Going to start grinding on these as I have time available.
Hoping I can stare at it a bit and come up with some way
to apply a clean solution in less than ''mumble'' hours.

[skliper]

See also #309, these are now reported as 'style' issues by cppcheck. No plan to fix style issues in test code.