Add F_DUPFD support to fcntl

[pickleburger]

I need to add F_DUPFD support to fcntl to make named working. There should be some modifications on nacl_repy and lind_glibc.

[JustinCappos]

Please make lind_glibc pass all flags through. The nacl_repy code can do the filtering and raise the unsupported call exception...