Regression test "integration.strlen (strlen.thumb.gcc.O0.g.elf)" fails on macOS

The `integration.strlen.Test_2017 (strlen.thumb.gcc.O0.g.elf)` regression test fails on macOS but succeeds on Linux and Windows.

## Input

Run the following regression test via [our testing framework](https://github.com/avast-tl/retdec-regression-tests-framework):
```
$ runner.py integration.strlen -r 'Test_2017.*strlen.thumb.gcc.O0.g.elf'
```

## Output

The test fails:
```
integration.strlen.Test_2017 (strlen.thumb.gcc.O0.g.elf) [ FAIL ] (5.85s)
F
======================================================================
FAIL: test_produce_expected_output (integration.strlen.Test_2017)
----------------------------------------------------------------------
Traceback (most recent call last):
File "retdec-regression-tests/integration/strlen/test.py", line 12, in test_produce_expected_output
expected_return_code=52
File "retdec-regression-tests-framework/regression_tests/tools/decompiler_test.py", line 86, in assert_c_produces_output_when_run
self.assertEqual(actual_return_code, expected_return_code, msg)
AssertionError: -6 != 52 : where the input was: aaaaaaaaaabbbbbbbbbbbbbbbbccccccccccccccdddddddddddd

----------------------------------------------------------------------
Ran 1 test in 0.214s

FAILED (failures=1)
```

## Expected output

The test should pass:
```
integration.strlen.Test_2017 (strlen.thumb.gcc.O0.g.elf) [ OK ] (5.72s)
```

## Configuration

* Commit: ae9a6d412caf73f1c93c7012a6f799de0cc95cdb (current `master`)
* 64b Arch Linux, GCC 7.3.1, Release build of RetDec
* mac OS 10.13, Apple LLVM version 9.0.0, Release build of RetDec

Start by running `runner.py integration.strlen -r 'Test_2017.*strlen.thumb.gcc.O0.g.elf'` on macOS and inspect `integration/strlen/test.py` together with `retdec-regression-tests-framework/regression_tests/tools/decompiler_test.py`. Compare the macOS return code with the expected value of 52; done means the named regression test passes on macOS as it does on Linux and Windows.

Written by the indexing model from the issue text.