merged fix from RC_0_16

git-svn-id: https://svn.code.sf.net/p/libtorrent/code/trunk@9890 a83610d8-ad2a-0410-a6ab-fc0612d85776
merge F_SETLF change from RC_0_16

git-svn-id: https://svn.code.sf.net/p/libtorrent/code/trunk@9893 a83610d8-ad2a-0410-a6ab-fc0612d85776
merged integer overflow fix from RC_0_16

git-svn-id: https://svn.code.sf.net/p/libtorrent/code/trunk@9895 a83610d8-ad2a-0410-a6ab-fc0612d85776