Don't crash if internal-char-font is called on non-GUI frames.

 src/fontset.c (Finternal_char_font): Return nil on non-GUI frames.
 (Bug#11964)

src/ChangeLog

+2012-11-26  Eli Zaretskii  <eliz@gnu.org>
+
+	* fontset.c (Finternal_char_font): Return nil on non-GUI frames.
+	(Bug#11964)
+
 2012-11-24  Paul Eggert  <eggert@cs.ucla.edu>
 	Revert recent change for Bug#8855.

src/fontset.c

@@ -1879,6 +1879,8 @@ DEFUN ("internal-char-font", Finternal_char_font, Sinternal_char_font, 1, 2, 0,
     }
   if (! CHAR_VALID_P (c))
     return Qnil;
+  if (!FRAME_WINDOW_P (f))
+    return Qnil;
   face_id = FACE_FOR_CHAR (f, FACE_FROM_ID (f, face_id), c, pos, Qnil);
   face = FACE_FROM_ID (f, face_id);
   if (face->font)