fails on ppc64 in test, which try to put to shmget()
size=-1. Size in shmget() is size_t which is unsigned,
so (int)(-1) will be retyped and shmget() gets 2^32-1
Bytes without problem.
This test is in Linux needless, because size_t is
unsigned at all archs and on other arch this fails
because 2^32-1>SHMMAX, I mean.
I suggest change size from int to size_t and wipe out
test with size=-1.
I didn't make mistake, I hope.