sizeof(event) not always equal to 12

[wegank]

By definition of epoll_event,

epoll-shim/include/sys/epoll.h

Lines 46 to 52 in 605be8c

	struct epoll_event {
	uint32_t events;
	epoll_data_t data;
	}
	#ifdef __x86_64__
	__attribute__((__packed__))
	#endif

the following test might fail on non-x86_64 platforms:

epoll-shim/test/epoll-test.c

Lines 343 to 346 in 605be8c

	struct epoll_event event;
	// this check works on 32bit _and_ 64bit, since
	// sizeof(epoll_event) == sizeof(uint32_t) + sizeof(uint64_t)
	ATF_REQUIRE(sizeof(event) == 12);

For example, on Linux / macOS on M1 (aarch64), the size should be 16.

[wegank]

Should be fixed by #34.