Edit numbers of core used by unreal compilation

File BuildConfiguration.xml are here : %appdata%\Unreal Engine\UnrealBuildTool

<?xml version="1.0" encoding="utf-8" ?>

<Configuration xmlns="https://www.unrealengine.com/BuildConfiguration">
        <BuildConfiguration>
                <MaxParallelActions>16</MaxParallelActions>
        </BuildConfiguration>
        <ParallelExecutor>
                <MaxProcessorCount>16</MaxProcessorCount>
                <ProcessorCountMultiplier>2</ProcessorCountMultiplier>
        </ParallelExecutor>
</Configuration>