* mmap syscall is special on Linux s390x because
the parameters for this syscall are passed as a struct
on user stack instead of registers.
* Introduce the SyscallTrampolines table into targets.Target
to address the above problem.
* There is a bug in Linux kernel s390x which causes QEMU TCG
to hang when KASAN is enabled. The bug has been fixed
in the forthcoming Linux 5.8 version. Until then do not enable
KASAN when using QEMU TCG, QEMU KVM shall have no problems with
KASAN.
Signed-off-by: Alexander Egorenkov <Alexander.Egorenkov@ibm.com>