[clang] [clang-tools-extra] [NFC] Explicitly pass a VFS when creating DiagnosticsEngine (PR #115852)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `lldb-aarch64-ubuntu` running on `linaro-lldb-aarch64-ubuntu` while building `clang-tools-extra,clang` at step 4 "build".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/59/builds/8551

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 4 (build) failure: build (failure)
...
431.158 [1335/10/5036] Building CXX object tools/lldb/source/Commands/CMakeFiles/lldbCommands.dir/CommandObjectVersion.cpp.o
431.159 [1335/9/5037] Building CXX object tools/lldb/source/Commands/CMakeFiles/lldbCommands.dir/CommandObjectType.cpp.o
431.167 [1335/8/5038] Building CXX object tools/lldb/source/Core/CMakeFiles/lldbCore.dir/AddressRange.cpp.o
431.167 [1335/7/5039] Building CXX object tools/lldb/source/Commands/CMakeFiles/lldbCommands.dir/CommandOptionsProcessAttach.cpp.o
431.167 [1335/6/5040] Building CXX object tools/lldb/source/Core/CMakeFiles/lldbCore.dir/AddressRangeListImpl.cpp.o
431.170 [1335/5/5041] Building CXX object tools/lldb/source/Commands/CMakeFiles/lldbCommands.dir/CommandOptionArgumentTable.cpp.o
431.173 [1335/4/5042] Building CXX object tools/lldb/source/Core/CMakeFiles/lldbCore.dir/Address.cpp.o
431.181 [1335/3/5043] Building CXX object tools/lldb/source/Core/CMakeFiles/lldbCore.dir/AddressResolver.cpp.o
431.182 [1335/2/5044] Building CXX object tools/lldb/source/Commands/CMakeFiles/lldbCommands.dir/CommandOptionsProcessLaunch.cpp.o
440.696 [1335/1/5045] Building CXX object tools/lldb/source/Commands/CMakeFiles/lldbCommands.dir/CommandObjectTarget.cpp.o
FAILED: tools/lldb/source/Commands/CMakeFiles/lldbCommands.dir/CommandObjectTarget.cpp.o 
/usr/local/bin/c++ -DGTEST_HAS_RTTI=0 -DHAVE_ROUND -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/tools/lldb/source/Commands -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/lldb/source/Commands -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/lldb/include -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/tools/lldb/include -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/include -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/llvm/include -I/usr/include/python3.10 -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/llvm/../clang/include -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/tools/lldb/../clang/include -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/lldb/source -I/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/tools/lldb/source -isystem /usr/include/libxml2 -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -Wno-unknown-pragmas -Wno-strict-aliasing -Wno-vla-extension -O3 -DNDEBUG -std=c++17  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -MD -MT tools/lldb/source/Commands/CMakeFiles/lldbCommands.dir/CommandObjectTarget.cpp.o -MF tools/lldb/source/Commands/CMakeFiles/lldbCommands.dir/CommandObjectTarget.cpp.o.d -o tools/lldb/source/Commands/CMakeFiles/lldbCommands.dir/CommandObjectTarget.cpp.o -c /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/lldb/source/Commands/CommandObjectTarget.cpp
../llvm-project/lldb/source/Commands/CommandObjectTarget.cpp:2203:14: error: no matching member function for call to 'createDiagnostics'
 2203 |     compiler.createDiagnostics();
      |     ~~~~~~~~~^~~~~~~~~~~~~~~~~
../llvm-project/clang/include/clang/Frontend/CompilerInstance.h:687:8: note: candidate function not viable: requires at least argument 'VFS', but no arguments were provided
  687 |   void createDiagnostics(llvm::vfs::FileSystem &VFS,
      |        ^                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
  688 |                          DiagnosticConsumer *Client = nullptr,
      |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  689 |                          bool ShouldOwnClient = true);
      |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~
../llvm-project/clang/include/clang/Frontend/CompilerInstance.h:710:3: note: candidate function not viable: requires at least 2 arguments, but 0 were provided
  710 |   createDiagnostics(llvm::vfs::FileSystem &VFS, DiagnosticOptions *Opts,
      |   ^                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  711 |                     DiagnosticConsumer *Client = nullptr,
      |                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  712 |                     bool ShouldOwnClient = true,
      |                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  713 |                     const CodeGenOptions *CodeGenOpts = nullptr);
      |                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/115852