[autofit] Reset the face charmap directly.

There is no need to validate the original charmap in `FT_Set_Charmap`.
It can be reset directly.

* src/autofit/afglobal.c (af_face_globals_compute_style_coverage):
Use direct assignment.
* src/autofit/af{latin,cjk,indic}.c (af_latin_metrics_init): Ditto.

src/autofit/afcjk.c

@@ -650,7 +650,7 @@
       af_cjk_metrics_check_digits( metrics, face );
     }
 
-    FT_Set_Charmap( face, oldmap );
+    face->charmap = oldmap;
     return FT_Err_Ok;
   }
 

src/autofit/afglobal.c

@@ -317,7 +317,7 @@
 
 #endif /* FT_DEBUG_LEVEL_TRACE */
 
-    FT_Set_Charmap( face, old_charmap );
+    face->charmap = old_charmap;
     return error;
   }
 

src/autofit/afindic.c

@@ -49,8 +49,7 @@
       af_cjk_metrics_check_digits( metrics, face );
     }
 
-    FT_Set_Charmap( face, oldmap );
-
+    face->charmap = oldmap;
     return FT_Err_Ok;
   }
 

src/autofit/aflatin.c

@@ -1157,7 +1157,7 @@
     }
 
   Exit:
-    FT_Set_Charmap( face, oldmap );
+    face->charmap = oldmap;
     return error;
   }