mono: tweak configuration to force sgen and 4.5 profile
mono: tweak configuration to force sgen and 4.5 profile

BigBrother-International/gst-cerbero,BigBrother-International/gst-cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,BigBrother-International/gst-cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,BigBrother-International/gst-cerbero,freedesktop-unofficial-mirror/gstreamer-sdk__cerbero,BigBrother-International/gst-cerbero