pptpd: bump to version 1.4.0 (fix bugs #12909, #15490, #15635)

pptpd: bump to version 1.4.0 (fix bugs #12909, #15490, #15635)

Old pptpd 1.3.4 suffers from an old bug that gcc 4.8 has apparently brought
to surface (analysed in bug #12909).

The problem has been fixed upstream and is included in 1.4.0 release from
October 2013.
http://sourceforge.net/p/poptop/mailman/message/30453437/
http://sourceforge.net/p/poptop/git/ci/db9a847936fa1c890d337ed609b9d3600834870a/
http://sourceforge.net/projects/poptop/

The patch bumps pptpd from 6-year old 1.3.4 to 1.4.0.

Related bugs #15428, #15635, #12909, #15490.
https://dev.openwrt.org/ticket/12909
https://dev.openwrt.org/ticket/15428  (AA12.09)
https://dev.openwrt.org/ticket/15490
https://dev.openwrt.org/ticket/15635

I have compiled and briefly tested on ar71xx/wndr3700 with trunk.

signed-off-by: hannu.nyman@iki.fi

git-svn-id: svn://svn.openwrt.org/openwrt/packages@40671 3c298f89-4303-0410-b956-a3cf2f4a3e73