configure.ac: add AM_SILENT_RULES and default yes
configure.ac: add AM_SILENT_RULES and default yes

ebu/ebu-bmx,xunchangguo/BMX,Limecraft/ebu-bmx,Limecraft/ebu-bmx,xunchangguo/BMX,stuarthicks/bmx,ebu/ebu-bmx,ebu/ebu-bmx,stuarthicks/bmx,stuarthicks/bmx,xunchangguo/BMX,Limecraft/ebu-bmx,kierank/bmxlib-bmx,kierank/bmxlib-bmx,kierank/bmxlib-bmx