Fix race condition in jump table list creation

src/IceCfg.cpp

Index: src/IceCfg.cpp
diff --git a/src/IceCfg.cpp b/src/IceCfg.cpp
index 65844b9f9872c03ddf45bfa00be1d0cee6b2eda3..3fe37f3c87eba936ee72bbf83c23955ec137db9f 100644
--- a/src/IceCfg.cpp
+++ b/src/IceCfg.cpp
@@ -966,12 +966,13 @@ void Cfg::emitJumpTables() {
     IceString MangledName = Ctx->mangleName(getFunctionName());
     for (const InstJumpTable *JumpTable : JumpTables) {
       SizeT NumTargets = JumpTable->getNumTargets();
-      JumpTableData &JT =
-          Ctx->addJumpTable(MangledName, JumpTable->getId(), NumTargets);
+      JumpTableData::TargetList TargetList;
       for (SizeT I = 0; I < NumTargets; ++I) {
         SizeT Index = JumpTable->getTarget(I)->getIndex();
-        JT.pushTarget(getAssembler()->getCfgNodeLabel(Index)->getPosition());
+        TargetList.emplace_back(
+            getAssembler()->getCfgNodeLabel(Index)->getPosition());
       }
+      Ctx->addJumpTable(MangledName, JumpTable->getId(), TargetList);
     }
   } break;
   case FT_Asm: {