elm theme - don't use empty env vars eina_prefix handles anyway

in 14ec825aa9 cedric added trying
ELM_DATA_DIR env var explicitly for looking for themes. first if this
is NULL then we look in a bogus directory (null). secondly eina_prefix
already takes care of env vars like thsi as part of figuring out
prefix with correct namespace etc. so this just is a bug as opposed to
anything useful and the CORRECt implementation is already done in
eina_prefix.

@fix

src/lib/elementary/elm_theme.c

@@ -94,14 +94,6 @@ _elm_theme_file_item_add(Elm_Theme_Files *files, const char *item, Eina_Bool pre
 
         eina_strbuf_reset(buf);
 
-        eina_strbuf_append_printf(buf,
-                                  "%s/themes/%s.edj",
-                                  getenv("ELM_DATA_DIR"), item);
-        f = eina_file_open(eina_strbuf_string_get(buf), EINA_FALSE);
-        _elm_theme_item_finalize(files, item, f, prepend, istheme);
-
-        eina_strbuf_reset(buf);
-
         eina_strbuf_append_printf(buf,
                                   "%s/themes/%s.edj",
                                   _elm_data_dir, item);