Fix minor bugs reported by the Coverity scan report.

Fix minor bugs reported by the Coverity scan report.

2006-04-10  Behdad Esfahbod  <behdad@gnome.org>

        Fix minor bugs reported by the Coverity scan report.

        * pango/opentype/harfbuzz-gdef.c (HB_GDEF_Build_ClassDefinition):
        * pango/opentype/harfbuzz-gpos.c (HB_GPOS_Query_Scripts),
        (HB_GPOS_Query_Languages), (HB_GPOS_Query_Features): Do not access
        structs before we check them for nullity.

        * pango/pango-layout.c (pango_layout_index_to_line),
        (pango_layout_index_to_line_and_extents),
        (pango_layout_index_to_pos): Check for invalid iterators outside the
        loop, so we don't crash.

        * pango/pango-layout.c (pango_layout_line_x_to_index): Set
        char_trailing instead of trailing in one of too many paths.  Should
        have been a typo.

        * pango/pangox.c (get_font_metrics_from_subfonts): Check for nullity
        somewhere.