linux-user/syscall.c: handle FUTEX_WAIT_BITSET in do_futex

linux-user/syscall.c: handle FUTEX_WAIT_BITSET in do_futex

Upstream libc has recently changed to start using
FUTEX_WAIT_BITSET instead of FUTEX_WAIT and this
is causing do_futex to return -TARGET_ENOSYS.

Pass bitset in val3 to sys_futex which will be
ignored by kernel for the FUTEX_WAIT case.

Signed-off-by: John Rigby <john.rigby@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
(cherry picked from commit cce246e0a21577bb2372ab3a7d6789371e087de9)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>