SILoadStoreOptimizer.cpp: Fix build; Clang doesn't like "using anonymous struct" since rL315256.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315283 91177308-0d34-0410-b5e6-96231b3b80d8

Author: chapuni

lib/Target/AMDGPU/SILoadStoreOptimizer.cpp

@@ -69,7 +69,7 @@ using namespace llvm;
 namespace {
 
 class SILoadStoreOptimizer : public MachineFunctionPass {
-  using CombineInfo = struct {
+  struct CombineInfo {
     MachineBasicBlock::iterator I;
     MachineBasicBlock::iterator Paired;
     unsigned EltSize;