Mark speexdsp effect as experimental.
Mark speexdsp effect as experimental.

davel/sox,jacksonh/sox,mhartzel/sox_personal_fork,uklauer/sox,CaptainHayashi/sox,MageSlayer/sox,MageSlayer/sox,CaptainHayashi/sox,Motiejus/sox,mhartzel/sox_personal_fork,Distrotech/sox,Distrotech/sox,pcqpcq/sox,davel/sox,MageSlayer/sox,mhartzel/sox_personal_fork,uklauer/sox,CaptainHayashi/sox,jacksonh/sox,MageSlayer/sox,mhartzel/sox_personal_fork,Distrotech/sox,cbagwell/sox,MageSlayer/sox,pcqpcq/sox,CaptainHayashi/sox,cbagwell/sox,Distrotech/sox,jacksonh/sox,jacksonh/sox,pcqpcq/sox,Motiejus/sox,pcqpcq/sox,uklauer/sox,davel/sox,davel/sox,cbagwell/sox,Motiejus/sox,Motiejus/sox,uklauer/sox,cbagwell/sox