[Tooling] Correct the total number of files being processed when `filter` is provided.

[ioeric]

lib/Tooling/AllTUsExecution.cpp

103

nit: if (match) then push_back would be a line shorter.

125

This is unused now

[hokein]

Address comments.

lib/Tooling/AllTUsExecution.cpp

auto AppendError = [&](llvm::Twine Err) {
     ErrorMsg += Err.str();
   };
 
   auto Log = [&](llvm::Twine Msg) {
     std::unique_lock<std::mutex> LockGuard(TUMutex);
     llvm::errs() << Msg.str() << "\n";
   };
 
-  auto Files = Compilations.getAllFiles();
+  std::vector<std::string> Files;
+  llvm::Regex RegexFilter(Filter);
+  for (const auto& File : Compilations.getAllFiles()) {
+    if (!RegexFilter.match(File))
+      continue;
+    Files.push_back(File);
+  }
   // Add a counter to track the progress.
   const std::string TotalNumStr = std::to_string(Files.size());
   unsigned Counter = 0;
   auto Count = [&]() {
     std::unique_lock<std::mutex> LockGuard(TUMutex);
     return ++Counter;
   };
 
   auto &Action = Actions.front();
 
   {
     llvm::ThreadPool Pool(ThreadCount == 0 ? llvm::hardware_concurrency()
                                            : ThreadCount);
     llvm::SmallString<128> InitialWorkingDir;
     if (auto EC = llvm::sys::fs::current_path(InitialWorkingDir)) {
       InitialWorkingDir = "";
       llvm::errs() << "Error while getting current working directory: "
                    << EC.message() << "\n";
     }
     llvm::Regex RegexFilter(Filter);
     for (std::string File : Files) {
-      if (!RegexFilter.match(File))
-        continue;
       Pool.async(
           [&](std::string Path) {
             Log("[" + std::to_string(Count()) + "/" + TotalNumStr +
                 "] Processing file " + Path);
             ClangTool Tool(Compilations, {Path});
             Tool.appendArgumentsAdjuster(Action.second);
             Tool.appendArgumentsAdjuster(getDefaultArgumentsAdjusters());
             for (const auto &FileAndContent : OverlayFiles)