swscale: cleanup unused code

Removed previous swscale code under '#ifndef NEW_FILTER'
and removed unused fields of SwsContext

libswscale/ppc/swscale_altivec.c

@@ -339,13 +339,13 @@ av_cold void ff_sws_init_swscale_ppc(SwsContext *c)
     }
     if (!is16BPS(dstFormat) && !is9_OR_10BPS(dstFormat) &&
         dstFormat != AV_PIX_FMT_NV12 && dstFormat != AV_PIX_FMT_NV21 &&
-        !c->alpPixBuf) {
+        !c->needAlpha) {
         c->yuv2planeX = yuv2planeX_altivec;
     }
 
     /* The following list of supported dstFormat values should
      * match what's found in the body of ff_yuv2packedX_altivec() */
-    if (!(c->flags & (SWS_BITEXACT | SWS_FULL_CHR_H_INT)) && !c->alpPixBuf) {
+    if (!(c->flags & (SWS_BITEXACT | SWS_FULL_CHR_H_INT)) && !c->needAlpha) {
         switch (c->dstFormat) {
         case AV_PIX_FMT_ABGR:
             c->yuv2packedX = ff_yuv2abgr_X_altivec;