retrieveLinuxMemoryStats() does not report the memory limits set by containers/cgroup

[mpirvu]

retrieveLinuxMemoryStats(struct OMRPortLibrary *portLibrary, struct J9MemoryInfo *memInfo) calls retrieveLinuxCgroupMemoryStats(portLibrary, &cgroupMemInfo); to determine the memory limits set by containers.
I have observed that retrieveLinuxCgroupMemoryStats() returns an error code and therefore retrieveLinuxMemoryStats() will only report the memory available on the host.
Additional tracing showed that retrieveLinuxCgroupMemoryStats() is actually able to determine the cgroup memory limits, but it fails when trying to determine the swapiness:

	rc = readCgroupSubsystemFile(portLibrary, OMR_CGROUP_SUBSYSTEM_MEMORY, CGROUP_MEMORY_SWAPPINESS, numItemsToRead, "%" SCNu64, &cgroupMemInfo->swappiness);
	if (0 != rc) {
		goto _exit;
	}

Maybe the code should not abort immediately and provide whatever partial information was able to gather correctly.

[mpirvu]

@babsingh Could you please comment on this issue? Thanks