dsp/enc.c: cosmetics: move DST() def closer to use
dsp/enc.c: cosmetics: move DST() def closer to use

Change-Id: Iccbcf046412426c2893b71eced517f611d2ffc3f

jiehu5114/libwebp,ttyangf/libwebp,jacklicn/libwebp,imazen/libwebp,yohunl/libwebp,ya7lelkom/libwebp,zofuthan/libwebp,jiehu5114/libwebp,PKRoma/libwebp,ttyangf/libwebp,Aexyn/libwebp,redengineer/libwebp,redengineer/libwebp,Aexyn/libwebp,gshORTON/webm.libwebp,abwiz0086/webm.libwebp,yohunl/libwebp,webmproject/libwebp,abwiz0086/webm.libwebp,jacklicn/libwebp,jacklicn/libwebp,ttyangf/libwebp,webmproject/libwebp,rxl194/libwebp,kalli123/webm.libwebp,yohunl/libwebp,abwiz0086/webm.libwebp,jacklicn/libwebp,gshORTON/webm.libwebp,rxl194/libwebp,kalli123/webm.libwebp,ya7lelkom/libwebp,yohunl/libwebp,rxl194/libwebp,ttyangf/libwebp,kalli123/webm.libwebp,Suvarna1488/webm.libwebp,PKRoma/libwebp,PKRoma/libwebp,imazen/libwebp,gshORTON/webm.libwebp,Suvarna1488/webm.libwebp,kalli123/webm.libwebp,yohunl/libwebp,zofuthan/libwebp,webmproject/libwebp,zofuthan/libwebp,Aexyn/libwebp,webmproject/libwebp,gshORTON/webm.libwebp,PKRoma/libwebp,ya7lelkom/libwebp,ya7lelkom/libwebp,jiehu5114/libwebp,imazen/libwebp,redengineer/libwebp,gshORTON/webm.libwebp,webmproject/libwebp,Aexyn/libwebp,imazen/libwebp,jiehu5114/libwebp,abwiz0086/webm.libwebp,kalli123/webm.libwebp,imazen/libwebp,jiehu5114/libwebp,redengineer/libwebp,abwiz0086/webm.libwebp,Suvarna1488/webm.libwebp,Suvarna1488/webm.libwebp,redengineer/libwebp,rxl194/libwebp,ya7lelkom/libwebp,PKRoma/libwebp,ttyangf/libwebp,zofuthan/libwebp,zofuthan/libwebp,Suvarna1488/webm.libwebp,Aexyn/libwebp,PKRoma/libwebp,rxl194/libwebp,jacklicn/libwebp