xfce-panel-plugin.bbclass: add x11 to REQUIRED_DISTRO_FEATURES
xfce-panel-plugin.bbclass: add x11 to REQUIRED_DISTRO_FEATURES

The bbclass depends on xfce4-panel and libxfce4ui
which require x11 distro feature.

Signed-off-by: Jackie Huang <49ec7cfe045884df7178a7e982697c7043dbc82b@windriver.com>
Signed-off-by: Martin Jansa <516df3ff67e1fa5d153800b15fb204c0a1a389dc@gmail.com>

openembedded/meta-openembedded,lgirdk/meta-openembedded,sigma-embedded/elito-org.openembedded.meta,openembedded/meta-openembedded,openembedded/meta-openembedded,amery/meta-openembedded,kraj/meta-openembedded,mrchapp/meta-openembedded,VCTLabs/meta-openembedded,lgirdk/meta-openembedded,schnitzeltony/meta-openembedded,kraj/meta-openembedded,sigma-embedded/elito-org.openembedded.meta,lgirdk/meta-openembedded,lgirdk/meta-openembedded,openembedded/meta-openembedded,sigma-embedded/elito-org.openembedded.meta,victronenergy/meta-openembedded,rehsack/meta-openembedded,mrchapp/meta-openembedded,moto-timo/meta-openembedded,VCTLabs/meta-openembedded,victronenergy/meta-openembedded,sigma-embedded/elito-org.openembedded.meta,rehsack/meta-openembedded,rehsack/meta-openembedded,mrchapp/meta-openembedded,mrchapp/meta-openembedded,kraj/meta-openembedded,victronenergy/meta-openembedded,rehsack/meta-openembedded,kraj/meta-openembedded,VCTLabs/meta-openembedded,amery/meta-openembedded,rehsack/meta-openembedded,kraj/meta-openembedded,victronenergy/meta-openembedded,sigma-embedded/elito-org.openembedded.meta,lgirdk/meta-openembedded,moto-timo/meta-openembedded,lgirdk/meta-openembedded,amery/meta-openembedded,VCTLabs/meta-openembedded,schnitzeltony/meta-openembedded,amery/meta-openembedded,victronenergy/meta-openembedded,moto-timo/meta-openembedded,amery/meta-openembedded,sigma-embedded/elito-org.openembedded.meta,victronenergy/meta-openembedded,moto-timo/meta-openembedded,openembedded/meta-openembedded,amery/meta-openembedded,rehsack/meta-openembedded,mrchapp/meta-openembedded,amery/meta-openembedded,schnitzeltony/meta-openembedded,amery/meta-openembedded,moto-timo/meta-openembedded,schnitzeltony/meta-openembedded,kraj/meta-openembedded,VCTLabs/meta-openembedded,VCTLabs/meta-openembedded,mrchapp/meta-openembedded,kraj/meta-openembedded,lgirdk/meta-openembedded,schnitzeltony/meta-openembedded,sigma-embedded/elito-org.openembedded.meta,VCTLabs/meta-openembedded,schnitzeltony/meta-openembedded,openembedded/meta-openembedded,VCTLabs/meta-openembedded,schnitzeltony/meta-openembedded,victronenergy/meta-openembedded,openembedded/meta-openembedded,rehsack/meta-openembedded,openembedded/meta-openembedded,mrchapp/meta-openembedded