-AC_CHECK_FUNCS([gettimeofday nl_langinfo strdup])
-AC_SEARCH_LIBS([aacEncOpen],[fdk-aac])
+AC_CHECK_FUNCS([sigaction gettimeofday nl_langinfo _vscprintf fseeko64])
+AC_CHECK_FUNC(getopt_long)
+AM_CONDITIONAL([FDK_NO_GETOPT_LONG],[test "$ac_cv_func_getopt_long" != "yes"])
+AC_SEARCH_LIBS([aacEncOpen],[fdk-aac],[],[],[])
+
+CHARSET_LIB=
+AC_CHECK_LIB([iconv], [locale_charset],
+ [CHARSET_LIB=-liconv],
+ [AC_CHECK_LIB([charset], [locale_charset], [CHARSET_LIB=-lcharset])])
+AC_SUBST([CHARSET_LIB])