Since the darray `sys_include_dirs` is an array of `char *`, it is
required to take a pointer to `char *`, that is `char **`. However,
`char *` was passed.
Since this function never called, another fix is removing entire
function `cf_preprocessor_add_sys_include_dir`.
Code submissions have continually suffered from formatting
inconsistencies that constantly have to be addressed. Using
clang-format simplifies this by making code formatting more consistent,
and allows automation of the code formatting so that maintainers can
focus more on the code itself instead of code formatting.
