Pass resource directory through to -print-target-info.

Author: DougGregor

Sources/SwiftDriver/Driver/Driver.swift

@@ -1583,8 +1583,13 @@ extension Driver {
         Triple($0, normalizing: true)
       }
 
-    // FIXME: Compute these.
-    let resourceDirPath: VirtualPath? = nil
+    // Determine the resource directory.
+    let resourceDirPath: VirtualPath?
+    if let resourceDirArg = parsedOptions.getLastArgument(.resourceDir) {
+      resourceDirPath = try VirtualPath(path: resourceDirArg.asSingle)
+    } else {
+      resourceDirPath = nil
+    }
 
     let toolchainType = try explicitTarget?.toolchainType(diagnosticsEngine) ??
           defaultToolchainType

Sources/SwiftDriver/Jobs/FrontendJobHelpers.swift

@@ -178,6 +178,11 @@ extension Driver {
       commandLine.appendPath(.absolute(workingDirectory))
     }
 
+    // Resource directory.
+    commandLine.appendFlag(.resourceDir)
+    commandLine.appendPath(
+      try AbsolutePath(validating: frontendTargetInfo.paths.runtimeResourcePath))
+
     // -g implies -enable-anonymous-context-mangled-names, because the extra
     // metadata aids debugging.
     if parsedOptions.getLast(in: .g) != nil {