Fix C++ interoperability flags

Author: DougGregor

Sources/SwiftDriver/Jobs/FrontendJobHelpers.swift

@@ -116,8 +116,8 @@ extension Driver {
     }
 
     // Add flags for C++ interop
-    if parsedOptions.hasArgument(.enableExperimentalCxxInterop) {
-      commandLine.appendFlag(.enableCxxInterop)
+    if parsedOptions.hasArgument(.enableCxxInterop) {
+      commandLine.appendFlag(.enableExperimentalCxxInterop)
     }
     if let stdlibVariant = parsedOptions.getLastArgument(.experimentalCxxStdlib)?.asSingle {
       commandLine.appendFlag("-Xcc")
@@ -152,7 +152,7 @@ extension Driver {
     try commandLine.appendLast(.enableLibraryEvolution, from: &parsedOptions)
     try commandLine.appendLast(.enableTesting, from: &parsedOptions)
     try commandLine.appendLast(.enablePrivateImports, from: &parsedOptions)
-    try commandLine.appendLast(.enableCxxInterop, from: &parsedOptions)
+    try commandLine.appendLast(.enableExperimentalCxxInterop, from: &parsedOptions)
     try commandLine.appendLast(in: .g, from: &parsedOptions)
     try commandLine.appendLast(.debugInfoFormat, from: &parsedOptions)
     try commandLine.appendLast(.importUnderlyingModule, from: &parsedOptions)