[clangd] Rename QueryDriverDatabase.cpp to SystemIncludeExtractor.cpp

[nridge]

fix comment

[nridge]

Follow-up to D133757

clang-tools-extra/clangd/CMakeLists.txt

add_clang_library(clangDaemon
   Quality.cpp
   ParsedAST.cpp
   Preamble.cpp
   RIFF.cpp
   Selection.cpp
   SemanticHighlighting.cpp
   SemanticSelection.cpp
   SourceCode.cpp
-  QueryDriverDatabase.cpp
+  SystemIncludeExtractor.cpp
   TidyProvider.cpp
   TUScheduler.cpp
   URI.cpp
   XRefs.cpp
   ${CMAKE_CURRENT_BINARY_DIR}/CompletionModel.cpp
 
   index/Background.cpp
   index/BackgroundIndexLoader.cpp

clang-tools-extra/clangd/SystemIncludeExtractor.cpp

-//===--- QueryDriverDatabase.cpp ---------------------------------*- C++-*-===//
+//===--- SystemIncludeExttor.cpp ---------------------------------*- C++-*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 // Some compiler drivers have implicit search mechanism for system headers.
 // This compilation database implementation tries to extract that information by
if (Lang.empty()) {
         elog("System include extraction: invalid file type for {0}", Ext);
         return;
       }
       Lang = driver::types::getTypeName(Type);
     }
 
     llvm::SmallString<128> Driver(Cmd.CommandLine.front());
     if (llvm::any_of(Driver,
-                       [](char C) { return llvm::sys::path::is_separator(C); }))
       // Driver is a not a single executable name but instead a path (either
       // relative or absolute).
       llvm::sys::fs::make_absolute(Cmd.Directory, Driver);
 
     if (auto Info =
             QueriedDrivers.get(/*Key=*/(Driver + ":" + Lang).str(), [&] {
               return extractSystemIncludesAndTarget(
                   Driver, Lang, Cmd.CommandLine, QueryDriverRegex);