linux-user: Fix 'mq_timedsend()' and 'mq_timedreceive()'

linux-user: Fix 'mq_timedsend()' and 'mq_timedreceive()'

Implementations of syscalls 'mq_timedsend()' and 'mq_timedreceive()'
in 'syscall.c' use functions 'target_to_host_timespec()' and
'host_to_target_timespec()' to transfer the value of 'struct timespec'
between target and host. However, the implementations don't check whether
this conversion succeeds and thus can cause an unaproppriate error instead
of the 'EFAULT (Bad address)' which is supposed to be set if the conversion
from target to host fails. This was confirmed with the modified LTP
test suite where test cases with a bad adress for 'timespec' were
added. This modified test suite can be found at:
https://github.com/bozutaf/ltp

Without the changes from this patch the bad adress testcase for 'mq_timedsend()'
succeds unexpectedly, while the test returns errno 'ETIMEOUT' for
'mq_timedreceive()':

mq_timedsend01.c:190: FAIL: mq_timedsend() returned 0, expected -1: SUCCESS (0)
mq_timedreceive01.c:178: FAIL: mq_timedreceive() failed unexpectedly,
expected EFAULT: ETIMEDOUT (110)

After the changes from this patch, testcases for both syscalls fail with EFAULT
as expected, which is the same test result that is received with native execution:

mq_timedsend01.c:187: PASS: mq_timedsend() failed expectedly: EFAULT (14)
mq_timedreceive01.c:180: PASS: mq_timedreceive() failed expectedly: EFAULT (14)

(Patch with this new test case will be sent to LTP mailing list soon)

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200824193752.67950-2-Filip.Bozuta@syrmia.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>