tril tests are not able to detect the right CPU level on Z

[dchopra001]

Removing a SKIP_ON_S390 check like the one below:

omr/fvtest/compilertriltest/VectorTest.cpp

Lines 313 to 322 in 149b524

	TR::VectorLength vl = std::get<1>(GetParam());
	TR::DataTypes et = scalarOpcode.getType().getDataType();
	SKIP_IF(vl > TR::NumVectorLengths, MissingImplementation) << "Vector length is not supported by the target platform";
	SKIP_ON_S390(KnownBug) << "This test is currently disabled on Z platforms because not all Z platforms have vector support (issue #1843)";
	SKIP_ON_S390X(KnownBug) << "This test is currently disabled on Z platforms because not all Z platforms have vector support (issue #1843)";
	TR::ILOpCode vectorOpcode = OMR::ILOpCode::convertScalarToVector(scalarOpcode.getOpCodeValue(), vl);
	ASSERT_NE(TR::BadILOp, vectorOpcode.getOpCodeValue());
	TR::DataType elementType = vectorOpcode.getType().getVectorElementType();

Results in Assertion failures on Z:

Assertion failed at /home/dchopra/openj9-openjdk-jdk17/omr/compiler/z/codegen/OMRInstruction.cpp:89:() cg->comp()->target().cpu.isAtLeast(_opcode.getMinimumALS())
	Processor detected (Unknown) does not support instruction VL

It looks like the processor is not detected properly. This is most likely happening because we call the default constructor for OMRCPU here:

omr/compiler/z/env/OMRCPU.cpp

Lines 34 to 42 in 0d4b2da

	TR::CPU
	OMR::Z::CPU::detect(OMRPortLibrary * const omrPortLib)
	{
	if (omrPortLib == NULL)
	return TR::CPU();
	OMRPORT_ACCESS_FROM_OMRPORT(omrPortLib);
	OMRProcessorDesc processorDescription;
	omrsysinfo_get_processor_description(&processorDescription);

The call to detect is made here:

omr/fvtest/compilertriltest/VectorTest.cpp

Lines 327 to 331 in 149b524

	char type[64];
	std::snprintf(type, sizeof(type), "Vector%i%s", vectorSize(vl) * 8, TR::DataType::getName(elementType));
	TR::CPU cpu = TR::CPU::detect(privateOmrPortLibrary);
	bool platformSupport = TR::CodeGenerator::getSupportsOpCodeForAutoSIMD(&cpu, loadOp) &&

Is privateOmrPortLibrary expected to be null here?