posix: Add ffs binding
posix: Add ffs binding

rvu95/vala,playya/vala,frida/vala,rvu95/vala,frida/vala,severinh/vala,GNOME/vala,jessevdk/vala,spidermonkdust/vala,flobrosch/vala-fixes,flobrosch/vala-fixes,frida/vala,tjol/vala-tjol,severinh/vala,jessevdk/vala,severinh/vala,GNOME/vala,xdave/pvala,spidermonkdust/vala,GNOME/vala,GNOME/vala,spidermonkdust/vala,playya/vala,playya/vala,Distrotech/vala,frida/vala,Distrotech/vala,flobrosch/vala-fixes,Distrotech/vala,tjol/vala-tjol,rvu95/vala,tjol/vala-tjol,jessevdk/vala,frida/vala