[clang][deps] Disable FileManager sharing with CASFS

(cherry picked from commit 85a6e90)

Author: jansvoboda11

clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp

@@ -472,6 +472,8 @@ class DependencyScanningAction : public tooling::ToolAction {
     // This will prevent us compiling individual modules asynchronously since
     // FileManager is not thread-safe, but it does improve performance for now.
     ScanInstance.getFrontendOpts().ModulesShareFileManager = true;
+    if (DepCASFS)
+      ScanInstance.getFrontendOpts().ModulesShareFileManager = false;
     ScanInstance.getHeaderSearchOpts().ModuleFormat = "raw";
     ScanInstance.getHeaderSearchOpts().ModulesIncludeVFSUsage =
         any(OptimizeArgs & ScanningOptimizations::VFS);