make waf runnable with mpirun when the directory is located under symbolic link

e.g.,
cwd = /home/foo/ns-3-dce, /home linked to /net/host/home
launch_dir = /net/host/home/foo/ns-3-dce
support changing timebase for DCE managed time (e.g., gettimeofday() and co)

syntax:
GlobalValue::Bind ("SimulationTimeBase", UintegerValue (time (NULL)));
fix inappropriate select (0, NULL, NULL, NULL, {non-null timeout})
add line feed after syslog lines
fix inappropriate setresgid checking
backports from ns-3-dce-dnssec (bind9, unbound support)