Pass str_t output param to _Wikitext_append_entity_from_utf32_char
Pass str_t output param to _Wikitext_append_entity_from_utf32_char

By accepting a str_t pointer instead of a char pointer the
two call sites of _Wikitext_append_entity_from_utf32_char
can be cleaned up a little.

Signed-off-by: Wincent Colaiuta <c76ac2e9cd86441713c7dfae92c451f3e6d17fdc@wincent.com>

barnaclebarnes/wikitext,wincent/wikitext,barnaclebarnes/wikitext,geni/wikitext,geni/wikitext,geni/wikitext,barnaclebarnes/wikitext,wincent/wikitext