Fix a memory leak in --dump-config

[nmathewson]

When freeing a configuration object from confparse.c in
dump_config(), we need to call the appropriate higher-level free
function (like or_options_free()) and not just config_free().

This only happens with options (since they're the one where
options_validate allocates extra stuff) and only when running
--dump-config with something other than minimal (since
OPTIONS_DUMP_MINIMAL doesn't hit this code).

Fixes bug 27893; bugfix on 0.3.2.1-alpha.

[coveralls]

Coverage increased (+0.003%) to 61.941% when pulling 8812f56 on nmathewson:bug27893 into de0b07c on torproject:master.