tumbler: ensure thumbnails work properly
tumbler: ensure thumbnails work properly

After some builds link tumbler-cache-plugin.so is not prperly created causing:
| Failed to load the cache plugin "tumbler-cache-plugin.so": /usr/lib/tumbler-1/plugins/cache/tumbler-cache-plugin.so: cannot open shared object file: No such file or directory

Signed-off-by: Andreas Müller <d72a15aaaca3a7afa855175c72dc8d2e05931e32@googlemail.com>
Signed-off-by: Armin Kuster <525edcd226fb27e7f47fbb319a38fe989c677548@gmail.com>

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