Fix boost::config tests

[nemothenoone]

Following failures fixes would be much appreciated:

bcm_test(NAME config_test_config_test_no_rtti SOURCES config_test.cpp)
set_target_properties(config_test_config_test_no_rtti PROPERTIES CXX_RTTI Off)
bcm_test(NAME config_test_config_test_no_exceptions SOURCES config_test.cpp)
set_target_properties(config_test_config_test_no_exceptions PROPERTIES CXX_EXCEPTIONS Off)

foreach(CONFIG_TEST config_test_config_test config_test_config_test_no_rtti config_test_config_test_no_exceptions)
target_link_libraries(${CONFIG_TEST} config_threads)
endforeach()```

```/config_test_config_test_no_exceptions.dir/config_test.cpp.o
In file included from /home/builder/boost/libs/config/test/config_test.cpp:51:
In file included from /home/builder/boost/libs/config/test/./boost_no_auto_ptr.ipp:13:
In file included from /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/memory:82:
In file included from /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/bits/shared_ptr_atomic.h:33:
/usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/bits/atomic_base.h:574:56: error: invalid application of 'sizeof' to an incomplete type 'void'
_M_type_size(ptrdiff_t d) const { return d * sizeof(_PTp); }```