patch from Roumen Petrov to detect if iconv() needs a const for the second

* config.h.in configure.in encoding.c: patch from Roumen Petrov
  to detect if iconv() needs a const for the second parameter
Daniel

svn path=/trunk/; revision=3693
diff --git a/config.h.in b/config.h.in
index 1dafc10..f8435d4 100644
--- a/config.h.in
+++ b/config.h.in
@@ -246,6 +246,9 @@
 /* Whether __va_copy() is available */
 #undef HAVE___VA_COPY
 
+/* Define as const if the declaration of iconv() needs const. */
+#undef ICONV_CONST
+
 /* Name of package */
 #undef PACKAGE