Improve LRU cache behavior in SelectorFlagsMap
Improve LRU cache behavior in SelectorFlagsMap

This code used to insert duplicate entries to avoid expensive shuffling
of the LRU cache.  With uluru this is no longer necessary, because
reordering the cache is cheap.

Now it uses the `LRUCache::find` method from uluru 0.2 to update entries
in-place.  This should improve the hit rate, because it eliminates
unnecessary evictions.

mattnenterprise/servo,SimonSapin/servo,rnestler/servo,DominoTree/servo,DominoTree/servo,nnethercote/servo,CJ8664/servo,sadmansk/servo,DominoTree/servo,pyfisch/servo,saneyuki/servo,szeged/servo,upsuper/servo,ConnorGBrewster/servo,saneyuki/servo,avadacatavra/servo,szeged/servo,avadacatavra/servo,nnethercote/servo,KiChjang/servo,peterjoel/servo,jimberlage/servo,pyfisch/servo,splav/servo,fiji-flo/servo,anthgur/servo,cbrewster/servo,CJ8664/servo,nnethercote/servo,larsbergstrom/servo,DominoTree/servo,thiagopnts/servo,cbrewster/servo,notriddle/servo,mattnenterprise/servo,mattnenterprise/servo,KiChjang/servo,splav/servo,ConnorGBrewster/servo,sadmansk/servo,CJ8664/servo,pyfisch/servo,thiagopnts/servo,KiChjang/servo,CJ8664/servo,rnestler/servo,pyfisch/servo,ConnorGBrewster/servo,notriddle/servo,rnestler/servo,paulrouget/servo,CJ8664/servo,mbrubeck/servo,anthgur/servo,cbrewster/servo,larsbergstrom/servo,upsuper/servo,KiChjang/servo,jimberlage/servo,cbrewster/servo,mattnenterprise/servo,pyfisch/servo,mbrubeck/servo,paulrouget/servo,dati91/servo,nnethercote/servo,thiagopnts/servo,saneyuki/servo,cbrewster/servo,KiChjang/servo,splav/servo,paulrouget/servo,saneyuki/servo,jimberlage/servo,larsbergstrom/servo,SimonSapin/servo,DominoTree/servo,SimonSapin/servo,canaltinova/servo,avadacatavra/servo,sadmansk/servo,splav/servo,canaltinova/servo,rnestler/servo,canaltinova/servo,mattnenterprise/servo,dati91/servo,canaltinova/servo,KiChjang/servo,peterjoel/servo,KiChjang/servo,sadmansk/servo,sadmansk/servo,mbrubeck/servo,notriddle/servo,ConnorGBrewster/servo,splav/servo,emilio/servo,jimberlage/servo,avadacatavra/servo,rnestler/servo,mbrubeck/servo,jimberlage/servo,nnethercote/servo,canaltinova/servo,thiagopnts/servo,anthgur/servo,emilio/servo,rnestler/servo,CJ8664/servo,saneyuki/servo,fiji-flo/servo,szeged/servo,paulrouget/servo,dati91/servo,notriddle/servo,SimonSapin/servo,saneyuki/servo,emilio/servo,dati91/servo,mbrubeck/servo,upsuper/servo,dati91/servo,splav/servo,KiChjang/servo,notriddle/servo,fiji-flo/servo,upsuper/servo,mattnenterprise/servo,szeged/servo,mbrubeck/servo,larsbergstrom/servo,sadmansk/servo,saneyuki/servo,upsuper/servo,anthgur/servo,splav/servo,pyfisch/servo,pyfisch/servo,larsbergstrom/servo,canaltinova/servo,notriddle/servo,paulrouget/servo,larsbergstrom/servo,ConnorGBrewster/servo,szeged/servo,anthgur/servo,peterjoel/servo,KiChjang/servo,nnethercote/servo,mbrubeck/servo,thiagopnts/servo,paulrouget/servo,avadacatavra/servo,CJ8664/servo,fiji-flo/servo,peterjoel/servo,canaltinova/servo,pyfisch/servo,cbrewster/servo,paulrouget/servo,dati91/servo,canaltinova/servo,SimonSapin/servo,notriddle/servo,paulrouget/servo,nnethercote/servo,jimberlage/servo,emilio/servo,rnestler/servo,anthgur/servo,fiji-flo/servo,notriddle/servo,emilio/servo,peterjoel/servo,cbrewster/servo,peterjoel/servo,jimberlage/servo,peterjoel/servo,KiChjang/servo,jimberlage/servo,nnethercote/servo,peterjoel/servo,saneyuki/servo,peterjoel/servo,emilio/servo,larsbergstrom/servo,SimonSapin/servo,emilio/servo,cbrewster/servo,szeged/servo,nnethercote/servo,SimonSapin/servo,mattnenterprise/servo,emilio/servo,notriddle/servo,upsuper/servo,notriddle/servo,szeged/servo,splav/servo,saneyuki/servo,DominoTree/servo,avadacatavra/servo,fiji-flo/servo,avadacatavra/servo,ConnorGBrewster/servo,sadmansk/servo,larsbergstrom/servo,emilio/servo,paulrouget/servo,szeged/servo,thiagopnts/servo,emilio/servo,thiagopnts/servo,saneyuki/servo,sadmansk/servo,DominoTree/servo,DominoTree/servo,nnethercote/servo,upsuper/servo,SimonSapin/servo,CJ8664/servo,splav/servo,mbrubeck/servo,peterjoel/servo,larsbergstrom/servo,anthgur/servo,rnestler/servo,dati91/servo,anthgur/servo,upsuper/servo,ConnorGBrewster/servo,jimberlage/servo,ConnorGBrewster/servo,szeged/servo,pyfisch/servo,pyfisch/servo,mattnenterprise/servo,larsbergstrom/servo,szeged/servo,avadacatavra/servo,splav/servo,dati91/servo,fiji-flo/servo,paulrouget/servo,DominoTree/servo,fiji-flo/servo,thiagopnts/servo,DominoTree/servo