Fix 'undefined symbol: locale_charset' when libiconv-1.17 is installed.

This allows the presence of locale_charset to indicate that -liconv is to be used.
Before libiconv-1.17, the locale_charset symbol was not exported (and
so locale_charset was not detected).

Fixes tlwg#25

configure.ac

@@ -62,20 +62,14 @@ if test $found_iconv = "no"; then
   AC_MSG_ERROR([*** No usable iconv() implementation found])
 fi
 
-case $with_libiconv in
-  gnu|native)
-    ICONV_LIBS="-liconv"
-    ;;
-esac
-AC_SUBST(ICONV_LIBS)
-
 #
 # Checks for locale_charset() and nl_langinfo(CODESET)
 #
 AC_CHECK_LIB(iconv, locale_charset,
              [have_locale_charset=yes], [have_locale_charset=no])
 if test x$have_locale_charset = xyes; then
   AC_DEFINE(HAVE_LOCALE_CHARSET,1,[Have locale_charset()])
+  with_libiconv=yes
 fi
 AC_CACHE_CHECK(
   [for nl_langinfo (CODESET)], datrie_cv_langinfo_codeset,
@@ -96,6 +90,13 @@ then
 Please consider installing GNU libiconv.])
 fi
 
+case $with_libiconv in
+  gnu|native|yes)
+    ICONV_LIBS="-liconv"
+    ;;
+esac
+AC_SUBST(ICONV_LIBS)
+
 
 # Checks for header files.
 AC_CHECK_HEADERS([limits.h stdlib.h stdio.h string.h])