[base] Make `find_unicode_charmap` a base function.

This is needed for forthcoming changes in the auto-hinter.

* include/freetype/internal/ftobjs.h, src/base/ftobjs.c: Updated.

include/freetype/internal/ftobjs.h

@@ -275,6 +275,28 @@ FT_BEGIN_HEADER
                   FT_GlyphSlot    slot,
                   FT_Render_Mode  mode );
 
+
+  /**************************************************************************
+   *
+   * @Function:
+   *   find_unicode_charmap
+   *
+   * @Description:
+   *   This function finds a Unicode charmap, if there is one.  And if there
+   *   is more than one, it tries to favour the more extensive one, i.e., one
+   *   that supports UCS-4 against those which are limited to the BMP (UCS-2
+   *   encoding.)
+   *
+   *   If a unicode charmap is found, `face->charmap` is set to it.
+   *
+   *   This function is called from `open_face`, from `FT_Select_Charmap(...,
+   *   FT_ENCODING_UNICODE)`, and also from `afadjust.c` in the 'autofit'
+   *   module.
+   */
+  FT_BASE( FT_Error )
+  find_unicode_charmap( FT_Face  face );
+
+
 #ifdef FT_CONFIG_OPTION_SUBPIXEL_RENDERING
 
   typedef void  (*FT_Bitmap_LcdFilterFunc)( FT_Bitmap*      bitmap,

src/base/ftobjs.c

@@ -1359,21 +1359,9 @@
   }
 
 
-  /**************************************************************************
-   *
-   * @Function:
-   *   find_unicode_charmap
-   *
-   * @Description:
-   *   This function finds a Unicode charmap, if there is one.
-   *   And if there is more than one, it tries to favour the more
-   *   extensive one, i.e., one that supports UCS-4 against those which
-   *   are limited to the BMP (said UCS-2 encoding.)
-   *
-   *   This function is called from open_face() (just below), and also
-   *   from FT_Select_Charmap( ..., FT_ENCODING_UNICODE ).
-   */
-  static FT_Error
+  /* documentation is in ftobjs.h */
+
+  FT_BASE_DEF( FT_Error )
   find_unicode_charmap( FT_Face  face )
   {
     FT_CharMap*  first;