hedgewars-engine (rust): fix "protocol_version" -> "hedgewars_engine_protocol_version"
That function/symbol was renamed in ef2fc0210362
<RCC>
<qresource prefix="/">
<file>main.qml</file>
<file>Page1.qml</file>
<file>Page1Form.ui.qml</file>
<file>qtquickcontrols2.conf</file>
<file>res/iconTime.png</file>
</qresource>
</RCC>