The old_mmap syscall (e.g. on i386) hands over the parameters in
a struct. Adjust the strace output to print the correct values.

Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: John Reiser <jreiser@BitWagon.com>
Closes: https://gitlab.com/qemu-project/qemu/-/issues/1760