Fix bug #7848 with using SET_SYMBOL_VALUE in image.c

!!!DO NOT MERGE TO THE TRUNK!!!

 image.c (syms_of_image): Don't use SET_SYMBOL_VALUE.

src/ChangeLog

+2011-01-16  Eli Zaretskii  <eliz@gnu.org>
+
+	* image.c (syms_of_image): Don't use SET_SYMBOL_VALUE.  (Bug#7848)
+
 2011-01-15  Martin Rudalics  <rudalics@gmx.at>
 	* window.c (inhibit_point_swap): New variable.

src/image.c

@@ -8464,9 +8464,9 @@ non-numeric, there is no explicit limit on the size of images.  */);
   Qlibpng_version = intern_c_string ("libpng-version");
   staticpro (&Qlibpng_version);
 #if HAVE_PNG
-  SET_SYMBOL_VAL (XSYMBOL (Qlibpng_version), make_number (PNG_LIBPNG_VER));
+  XSYMBOL (Qlibpng_version)->value = make_number (PNG_LIBPNG_VER);
 #else
-  SET_SYMBOL_VAL (XSYMBOL (Qlibpng_version), make_number (-1));
+  XSYMBOL (Qlibpng_version)->value = make_number (-1));
 #endif
 #endif