[llvm-jitlink] Use std::optional::value_or (NFC) (#140173)

Author: kazutakahirata

llvm/tools/llvm-jitlink/llvm-jitlink.cpp

@@ -1243,7 +1243,7 @@ Session::Session(std::unique_ptr<ExecutorProcessControl> EPC, Error &Err)
       if ((Err = ES.getBootstrapMapValue<bool, bool>("darwin-use-ehframes-only",
                                                      ForceEHFrames)))
         return;
-      bool UseEHFrames = ForceEHFrames ? *ForceEHFrames : false;
+      bool UseEHFrames = ForceEHFrames.value_or(false);
       if (!UseEHFrames)
         ObjLayer.addPlugin(ExitOnErr(UnwindInfoRegistrationPlugin::Create(ES)));
       else