elm_index: include horizontal index to omit calculation

elm_index: include horizontal index to omit calculation

    Summary:
    - when index is set to horizontal by elm_index_horizontal_set()
      there is no logic about omit calculation. However, when
      omit is enabled/disabled by elm_index_omit_enabled_set(),
      horizontal index is ignored by
      if (sd->orientation == EFL_ORIENT_HORIZONTAL) return;
    - This can cause inconsistency when order of calling those APIs
      is changed. And also, that "horizontal index cannot be omitted" is not documented
      and does not make sense.
    - This commit enables omit for horizontal index, but further
      change is needed because current logic of getting min_w for
      dummy edje object is not accurate when text is set.

Change-Id: I26a092465e05c2008875fff16a6f30e0850e7c18
Signed-off-by: Sungtaek Hong <sth253.hong@samsung.com>
origin: upstream