configure: remove iconv check

As it is not used by Suricata and libhtp does check for it itself

configure.ac

@@ -1608,8 +1608,6 @@
             # make sure libhtp is added to the includes
             CPPFLAGS="-I\${srcdir}/../libhtp/ ${CPPFLAGS}"
 
-            AC_CHECK_HEADER(iconv.h,,[AC_MSG_ERROR(iconv.h not found ...)])
-            AC_CHECK_LIB(iconv, libiconv_close)
             AC_DEFINE_UNQUOTED([HAVE_HTP_URI_NORMALIZE_HOOK],[1],[Assuming htp_config_register_request_uri_normalize function in bundled libhtp])
             AC_DEFINE_UNQUOTED([HAVE_HTP_TX_GET_RESPONSE_HEADERS_RAW],[1],[Assuming htp_tx_get_response_headers_raw function in bundled libhtp])
             AC_DEFINE_UNQUOTED([HAVE_HTP_DECODE_QUERY_INPLACE],[1],[Assuming htp_decode_query_inplace function in bundled libhtp])