llvm::make_unique is gone from LLVM trunk

(but when targeting older versions of LLVM/Clang, COMPILER_PLUGINS_CXX can still
specify -std=c++11)

Change-Id: I1b91f2817516d015bc12b6a3faf1874ab938a3ae
Reviewed-on: https://gerrit.libreoffice.org/77866
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

compilerplugins/clang/pluginhandler.cxx

@@ -11,6 +11,7 @@
 
 #include <memory>
 #include <system_error>
+#include <utility>
 
 #include "plugin.hxx"
 #include "pluginhandler.hxx"
@@ -385,7 +386,11 @@ void PluginHandler::HandleTranslationUnit( ASTContext& context )
 
 std::unique_ptr<ASTConsumer> LibreOfficeAction::CreateASTConsumer( CompilerInstance& Compiler, StringRef )
 {
+#if __cplusplus >= 201402L
+    return std::make_unique<PluginHandler>( Compiler, _args );
+#else
     return llvm::make_unique<PluginHandler>( Compiler, _args );
+#endif
 }
 
 bool LibreOfficeAction::ParseArgs( const CompilerInstance&, const std::vector< std::string >& args )