Make `seac' operator work correctly with incremental interface.

SEAC (Single Encoding Accented Characters) are composed of (basically) two
indices specifying two other glyphs, and a movement to position the accent
properly with respect to the main glyph.

To make it work with the incremental interface we now demand that the caller
handles the encoding by itself.

src/psaux/t1decode.c

@@ -206,9 +206,19 @@
       return PSaux_Err_Syntax_Error;
     }
 
+#ifdef FT_CONFIG_OPTION_INCREMENTAL
+
+    /* the caller must handle the font encoding also */
+    bchar_index = bchar;
+    achar_index = achar;
+
+#else
+
     bchar_index = t1_lookup_glyph_by_stdcharcode( decoder, bchar );
     achar_index = t1_lookup_glyph_by_stdcharcode( decoder, achar );
 
+#endif
+
     if ( bchar_index < 0 || achar_index < 0 )
     {
       FT_ERROR(( "t1operator_seac:" ));