Headless: Set softgpu config flag.

This affects dump playback (whether it updates RAM with what's in the
frame dump), so it's confusing when it's not set matching the core.

headless/Headless.cpp

@@ -416,6 +416,7 @@ int main(int argc, const char* argv[])
 	g_Config.bEnableLogging = fullLog;
 	g_Config.bSoftwareSkinning = true;
 	g_Config.bVertexDecoderJit = true;
+	g_Config.bSoftwareRendering = coreParameter.gpuCore == GPUCORE_SOFTWARE;
 	g_Config.bSoftwareRenderingJit = true;
 	g_Config.bBlockTransferGPU = true;
 	g_Config.iSplineBezierQuality = 2;