Unconditionally call __gconv_get_path when reading iconv configuration

__gconv_read_conf is only ever called once during the program's lifetime.
This means that __gconv_path_elem is always uninitialized when the function
begins executing.  __gconv_get_path has an assert to ensure that this
expected runtime behaviour is always exhibited.  Given this, checking for a
NULL value before calling __gconv_get_path is unnecessary.  This commit
drops the condition and calls __gconv_get_path unconditionally.