[clangd] Strip plugin arguments in clangd-indexer.

[hokein]

Summary

This would allow clangd-indexer runs on chromium repo.

clangd/indexer/IndexerMain.cpp

 //===----------------------------------------------------------------------===//
 
 #include "index/IndexAction.h"
 #include "index/Merge.h"
 #include "index/Ref.h"
 #include "index/Serialization.h"
 #include "index/Symbol.h"
 #include "index/SymbolCollector.h"
+#include "clang/Tooling/ArgumentsAdjusters.h"
 #include "clang/Tooling/CommonOptionsParser.h"
 #include "clang/Tooling/Execution.h"
 #include "clang/Tooling/Tooling.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Signals.h"
 
 namespace clang {
 namespace clangd {
int main(int argc, const char **argv) {
   if (!Executor) {
     llvm::errs() << llvm::toString(Executor.takeError()) << "\n";
     return 1;
   }
 
   // Collect symbols found in each translation unit, merging as we go.
   clang::clangd::IndexFileIn Data;
   auto Err = Executor->get()->execute(
-      llvm::make_unique<clang::clangd::IndexActionFactory>(Data));
+      llvm::make_unique<clang::clangd::IndexActionFactory>(Data),
+      clang::tooling::getStripPluginsAdjuster());
   if (Err) {
     llvm::errs() << llvm::toString(std::move(Err)) << "\n";
   }
 
   // Emit collected data.
   clang::clangd::IndexFileOut Out(Data);
   Out.Format = clang::clangd::Format;
   llvm::outs() << Out;
   return 0;
 }