Adjust emitted IR on !llvm.used.conditional to match LLVM expectations (swiftlang#39715)

Author: kubamracek

lib/IRGen/GenDecl.cpp

@@ -3720,7 +3720,10 @@ static void appendLLVMUsedConditionalEntry(IRGenModule &IGM,
           llvm::Type::getInt32Ty(IGM.Module.getContext()), 0)),
       // (3) the "edge" that holds the target alive, if it's missing the target
       // is allowed to be removed
-      llvm::ConstantAsMetadata::get(dependsOn),
+      llvm::MDNode::get(IGM.Module.getContext(),
+                        {
+                            llvm::ConstantAsMetadata::get(dependsOn),
+                        }),
   };
   auto *usedConditional =
       IGM.Module.getOrInsertNamedMetadata("llvm.used.conditional");

test/IRGen/conditional-dead-strip-ir.swift

@@ -26,9 +26,18 @@ public enum Enum {
 // CHECK-SAME: ], section "llvm.metadata"
 
 // CHECK:      !llvm.used.conditional = !{[[C1:!.*]], [[C2:!.*]], [[C3:!.*]], [[C4:!.*]], [[C5:!.*]]}
-// CHECK:      [[C1]]  = !{{{.*}} @"$s4main11TheProtocolHr", i32 0, {{.*}} @"$s4main11TheProtocolMp"}
+
+// CHECK:      [[C1]]  = !{{{.*}} @"$s4main11TheProtocolHr", i32 0, [[C1A:!.*]]}
+// CHECK:      [[C1A]] = !{{{.*}} @"$s4main11TheProtocolMp"}
+
 // CHECK:      [[C2]]  = !{{{.*}} @"$s4main5ClassCAA11TheProtocolAAHc", i32 1, [[C2A:!.*]]}
 // CHECK:      [[C2A]] = !{{{.*}} @"$s4main11TheProtocolMp", {{.*}} @"$s4main5ClassCMn"}
-// CHECK:      [[C3]]  = !{{{.*}} @"$s4main5ClassCHn", i32 0, {{.*}} @"$s4main5ClassCMn"}
-// CHECK:      [[C4]]  = !{{{.*}} @"$s4main6StructVHn", i32 0, {{.*}} @"$s4main6StructVMn"}
-// CHECK:      [[C5]]  = !{{{.*}} @"$s4main4EnumOHn", i32 0, {{.*}} @"$s4main4EnumOMn"}
+
+// CHECK:      [[C3]]  = !{{{.*}} @"$s4main5ClassCHn", i32 0, [[C3A:!.*]]}
+// CHECK:      [[C3A]] = !{{{.*}} @"$s4main5ClassCMn"}
+
+// CHECK:      [[C4]]  = !{{{.*}} @"$s4main6StructVHn", i32 0, [[C4A:!.*]]}
+// CHECK:      [[C4A]] = !{{{.*}} @"$s4main6StructVMn"}
+
+// CHECK:      [[C5]]  = !{{{.*}} @"$s4main4EnumOHn", i32 0, [[C5A:!.*]]}
+// CHECK:      [[C5A]] = !{{{.*}} @"$s4main4EnumOMn"}