syscalls: Add basic futex testcases

* futex_wait01 - tests ETIMEDOUT and EWOULDBLOCK
* futex_wait02 - tests sleeping on futex
* futex_wait03 - tests sleeping on PRIVATE futex
* futex_wait04 - tests futex on uninitialized mapped memory
                 (ported from futextest, likely regression test)

* futex_wake01 - tests wake when nobody sleeps on given futex
* futex_wake02 - tests waking up with several threads with PRIVATE futex
* futex_wake03 - tests waking up with several processes

This is only first batch of the planned testcses. What is missing is
futex reqeueing, priority inheritance futexes, bitset futexes and maybe
more.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
12 files changed