radeon/llvm: Disable SI flow control again for now.

It makes piglit unreliable due to VM protection faults and GPU lockups.

Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Tom Stellard <thomas.stellard@amd.com>

src/gallium/drivers/radeon/AMDGPUTargetMachine.cpp

@@ -134,7 +134,8 @@ bool AMDGPUPassConfig::addPreEmitPass() {
     addPass(FinalizeMachineBundlesID);
   } else {
     PM->add(createSILowerLiteralConstantsPass(*TM));
-    PM->add(createSILowerFlowControlPass(*TM));
+    // piglit is unreliable (VM protection faults, GPU lockups) with this pass:
+    //PM->add(createSILowerFlowControlPass(*TM));
   }
 
   return false;