Fix OperandStackTests Thread->sp field type

The definition of this type has an extra level of indirection
that is not warranted and is actually incorrect. The only reason we
didn't find it is because this test is no longer executed by
default on platforms that support it (i.e. x86 for the time being).

Signed-off-by: Mark Stoodley <mstoodle@ca.ibm.com>

jitbuilder/release/cpp/samples/OperandStackTests.cpp

@@ -585,7 +585,7 @@ OperandStackTestUsingStructMethod::OperandStackTestUsingStructMethod(OMR::JitBui
    : OperandStackTestMethod(d)
    {
    d->DefineStruct("Thread");
-   d->DefineField("Thread", "sp", d->PointerTo(d->PointerTo(STACKVALUEILTYPE)), offsetof(Thread, sp));
+   d->DefineField("Thread", "sp", d->PointerTo(STACKVALUEILTYPE), offsetof(Thread, sp));
    d->CloseStruct("Thread");
 
    DefineParameter("thread", d->PointerTo("Thread"));