zero errno before calling decode from the call table

src/vmod_blobcode.c

@@ -225,6 +225,7 @@ vmod_blob__init(VRT_CTX, struct vmod_blobcode_blob **blobp, const char *vcl_name
 	}
 
 	va_start(ap, p);
+	errno = 0;
 	len = func[dec].decode(dec, b->blob.priv, len, p, ap);
 	va_end(ap);
 
@@ -355,6 +356,7 @@ vmod_decode(VRT_CTX, VCL_ENUM decs, const char *p, ...) {
 	buf = wb_buf(&wb);
 
 	va_start(ap, p);
+	errno = 0;
 	len = func[dec].decode(dec, buf, wb_space(&wb), p, ap);
 	va_end(ap);
 
@@ -443,6 +445,7 @@ vmod_transcode(VRT_CTX, VCL_ENUM decs, VCL_ENUM encs, const char *p, ...) {
 	char buf[l];
 
 	va_start(ap, p);
+	errno = 0;
 	len = func[dec].decode(dec, buf, l, p, ap);
 	va_end(ap);