update to new VCL_BLOB

Ref: https://github.com/varnishcache/varnish-cache/commit/5450550906d0809dfc21ae9d3a5b14446c1809d4

src/vmod_blobsynth.c

@@ -12,7 +12,7 @@
 #include "vcc_blobsynth_if.h"
 
 VCL_VOID
-vmod_synthetic(VRT_CTX, VCL_BLOB blob)
+vmod_synthetic(VRT_CTX, VCL_BLOB body)
 {
 	struct vsb *vsb;
 
@@ -25,10 +25,10 @@ vmod_synthetic(VRT_CTX, VCL_BLOB blob)
 
 	CAST_OBJ_NOTNULL(vsb, ctx->specific, VSB_MAGIC);
 
-	if (blob == NULL || blob->len == 0)
+	if (body == NULL || body->len == 0)
 		return;
-	AN(blob->priv);
-	if (VSB_bcat(vsb, blob->priv, blob->len))
+	AN(body->blob);
+	if (VSB_bcat(vsb, body->blob, body->len))
 		VRT_fail(ctx, "blobsynth.synthetic(): %s",
 		strerror(VSB_error(vsb)));
 }