* src/cid/cidriver.c: Clean up interface.

Ensure that all driver functions use the signature of the service or driver.
This avoids pointer mismatches, which are technically undefined behaviour.
Recent compilers are more picky in catching them as part of Control Flow
Integrity tests.
diff --git a/src/cid/cidriver.c b/src/cid/cidriver.c
index 9669eb7..fd015ef 100644
--- a/src/cid/cidriver.c
+++ b/src/cid/cidriver.c
@@ -48,10 +48,11 @@
    *
    */
 
-  static const char*
-  cid_get_postscript_name( CID_Face  face )
+  FT_CALLBACK_DEF( const char* )
+  cid_get_postscript_name( FT_Face  face )    /* CID_Face */
   {
-    const char*  result = face->cid.cid_font_name;
+    CID_Face     cidface = (CID_Face)face;
+    const char*  result  = cidface->cid.cid_font_name;
 
 
     if ( result && result[0] == '/' )
@@ -72,24 +73,26 @@
    *
    */
 
-  static FT_Error
-  cid_ps_get_font_info( FT_Face          face,
+  FT_CALLBACK_DEF( FT_Error )
+  cid_ps_get_font_info( FT_Face          face,        /* CID_Face */
                         PS_FontInfoRec*  afont_info )
   {
-    *afont_info = ((CID_Face)face)->cid.font_info;
+    *afont_info = ( (CID_Face)face )->cid.font_info;
 
     return FT_Err_Ok;
   }
 
-  static FT_Error
-  cid_ps_get_font_extra( FT_Face          face,
-                        PS_FontExtraRec*  afont_extra )
+
+  FT_CALLBACK_DEF( FT_Error )
+  cid_ps_get_font_extra( FT_Face           face,         /* CID_Face */
+                         PS_FontExtraRec*  afont_extra )
   {
-    *afont_extra = ((CID_Face)face)->font_extra;
+    *afont_extra = ( (CID_Face)face )->font_extra;
 
     return FT_Err_Ok;
   }
 
+
   static const FT_Service_PsInfoRec  cid_service_ps_info =
   {
     (PS_GetFontInfoFunc)   cid_ps_get_font_info,   /* ps_get_font_info    */
@@ -107,13 +110,14 @@
    * CID INFO SERVICE
    *
    */
-  static FT_Error
-  cid_get_ros( CID_Face      face,
+  FT_CALLBACK_DEF( FT_Error )
+  cid_get_ros( FT_Face       face,        /* CID_Face */
                const char*  *registry,
                const char*  *ordering,
                FT_Int       *supplement )
   {
-    CID_FaceInfo  cid = &face->cid;
+    CID_Face      cidface = (CID_Face)face;
+    CID_FaceInfo  cid     = &cidface->cid;
 
 
     if ( registry )
@@ -129,8 +133,8 @@
   }
 
 
-  static FT_Error
-  cid_get_is_cid( CID_Face  face,
+  FT_CALLBACK_DEF( FT_Error )
+  cid_get_is_cid( FT_Face   face,    /* CID_Face */
                   FT_Bool  *is_cid )
   {
     FT_Error  error = FT_Err_Ok;
@@ -144,12 +148,13 @@
   }
 
 
-  static FT_Error
-  cid_get_cid_from_glyph_index( CID_Face  face,
+  FT_CALLBACK_DEF( FT_Error )
+  cid_get_cid_from_glyph_index( FT_Face   face,        /* CID_Face */
                                 FT_UInt   glyph_index,
                                 FT_UInt  *cid )
   {
-    FT_Error  error = FT_Err_Ok;
+    FT_Error  error   = FT_Err_Ok;
+    CID_Face  cidface = (CID_Face)face;
 
 
     /*
@@ -158,7 +163,7 @@
      * array or dictionary.  Fonts loaded by the incremental loading feature
      * are thus not handled here.
      */
-    error = cid_compute_fd_and_offsets( face, glyph_index,
+    error = cid_compute_fd_and_offsets( cidface, glyph_index,
                                         NULL, NULL, NULL );
     if ( error )
       *cid = 0;
@@ -218,7 +223,6 @@
   }
 
 
-
   FT_CALLBACK_TABLE_DEF
   const FT_Driver_ClassRec  t1cid_driver_class =
   {