message: [unittests] Fix TestSwiftASTContext
  Initialize the file system.
diff: #include "gtest/gtest.h"
  +#include "lldb/Host/FileSystem.h"
  #include "lldb/Host/HostInfo.h"
  #include "lldb/Symbol/SwiftASTContext.h"
  @@ -49,9 +50,14 @@ struct TestSwiftASTContext : public testing::Test {
  ASSERT_NO_ERROR(fs::remove_directories(m_base_dir));
  }
  - static void SetUpTestCase() { HostInfo::Initialize(); }
  + static void SetUpTestCase() {
  + FileSystem::Initialize();
  + HostInfo::Initialize(); }
  - static void TearDownTestCase() { HostInfo::Terminate(); }
  + static void TearDownTestCase() {
  + HostInfo::Terminate();
  + FileSystem::Terminate();
  + }
  };
  struct SwiftASTContextTester : public SwiftASTContext {
  