[FIX] replaced integer overflow test with getconf

- Integer overflow test does not worked properly and is not reliable
   indicator of host architecture, it replaced with "getconf LONG_BIT"
   that was tested and worked properly on Ubuntu 14.04.
   now wkhtml2pdf downloads are correctly adapted to x64 and x32 hosts.

V9/odoo_install.sh

@@ -86,7 +86,7 @@ sudo apt-get install python-gevent -y
 if [ $INSTALL_WKHTMLTOPDF = "True" ]; then
   echo -e "\n---- Install wkhtml and place shortcuts on correct place for ODOO 9 ----"
   #pick up correct one from x64 & x32 versions:
-  if ((1<<32));then
+  if [ "`getconf LONG_BIT`" == "64" ];then
       _url=$WKHTMLTOX_X64
   else
       _url=$WKHTMLTOX_X32