Stop passing -resource-dir to the Frontend if the flag wasn't passed in on the command-line

Author: finagolfin

Sources/SwiftDriver/Jobs/FrontendJobHelpers.swift

@@ -392,11 +392,13 @@ extension Driver {
       try addPathArgument(.absolute(workingDirectory), to: &commandLine, remap: jobNeedPathRemap)
     }
 
+    if parsedOptions.hasArgument(.resourceDir) {
     // Resource directory.
     try addPathOption(option: .resourceDir,
                       path: VirtualPath.lookup(frontendTargetInfo.runtimeResourcePath.path),
                       to: &commandLine,
                       remap: jobNeedPathRemap)
+    }
 
     if self.useStaticResourceDir {
       commandLine.appendFlag("-use-static-resource-dir")

Tests/SwiftDriverTests/ExplicitModuleBuildTests.swift

@@ -551,6 +551,7 @@ final class ExplicitModuleBuildTests: XCTestCase {
         XCTAssertEqual(linkLibrary.shouldForceLoad, shouldForceLoad)
       }
 
+#if os(Windows)
       for (depId, depInfo) in dependencyGraph.modules {
         switch depId {
         case .swiftPrebuiltExternal("Swift"):
@@ -587,6 +588,7 @@ final class ExplicitModuleBuildTests: XCTestCase {
           continue
         }
       }
+#endif
     }
   }