(lookup_encoding_0, lookup_encoding_2)

(lookup_encoding_0, lookup_encoding_2)
(lookup_encoding_4, lookup_encoding_6, lookup_encoding_8)
(lookup_encoding_10, lookup_encoding_12): Arguments and return
value changed.
(lookup_cmap_func): New function type.
(lookup_cmap_func_table): New variable.
(get_GlyphID): New function.
(get_uvs_glyph): Call get_GlyphID instead of directly accessing
cmal->unicode_table.
(OTF_drive_cmap, OTF_drive_cmap2): Call one of lookup functions in
lookup_cmap_func_table.