Revert^3 "ART: Reference.getReferent intrinsic for x86 and x86_64"

Reverting because GenerateCalleeMethodStaticOrDirectCall()
prevents replacing kDexCacheViaMethod with kRuntimeCall
where we would not retrieve the target method at all and
leave the runtime to retrieve and call it just like for
unresolved methods.

The intrinsic should be re-implemented by loading the
flags through HLoadClass.

Note that the intrinsic was unimplemented for CC.

Test: Rely on TreeHugger.
Bug: 32535355
Bug: 30627598

This reverts commit 288c7a86.

Change-Id: Ia22864553ff55562897571e180b11926ccd51588