gpu-compute: Fix bug with return in cfg

Connecting basic blocks would stop too early in kernels where ret was not the
last instruction.  This patch allows basic blocks after the ret instruction
to be properly connected.

src/gpu-compute/kernel_cfg.cc

@@ -139,7 +139,7 @@ ControlFlowInfo::connectBasicBlocks()
         GPUStaticInst* last = lastInstruction(bb.get());
         if (last->o_type == Enums::OT_RET) {
             bb->successorIds.insert(exit_bb->id);
-            break;
+            continue;
         }
         if (last->o_type == Enums::OT_BRANCH) {
             const uint32_t target_pc = last->getTargetPc();