fix libde265 on ancient debian OS?

src/SPC/builder/unix/library/libde265.php

@@ -11,6 +11,7 @@ trait libde265
     protected function build(): void
     {
         UnixCMakeExecutor::create($this)
+            ->appendEnv(['LDFLAGS' => '-lpthread'])
             ->addConfigureArgs('-DENABLE_SDL=OFF')
             ->build();
         $this->patchPkgconfPrefix(['libde265.pc']);