Fix memory leak in imagemagick-types

* src/image.c (Fimagemagick_types): Use AcquireExceptionInfo to
avoid memory leak.

src/image.c

@@ -8885,13 +8885,13 @@ and `imagemagick-types-inhibit'.  */)
 {
   Lisp_Object typelist = Qnil;
   size_t numf = 0;
-  ExceptionInfo ex;
+  ExceptionInfo *ex;
   char **imtypes;
   size_t i;
 
-  GetExceptionInfo(&ex);
-  imtypes = GetMagickList ("*", &numf, &ex);
-  DestroyExceptionInfo(&ex);
+  ex = AcquireExceptionInfo ();
+  imtypes = GetMagickList ("*", &numf, ex);
+  DestroyExceptionInfo (ex);
 
   for (i = 0; i < numf; i++)
     {