xdrgen: Fix code generated for counted arrays

When an XDR counted array has a maximum element count, xdrgen adds
a bounds check to the encoder or decoder for that type. But in cases
where the .x provides no maximum element count, such as

struct notify4 {
        /* composed from notify_type4 or notify_deviceid_type4 */
        bitmap4         notify_mask;
        notifylist4     notify_vals;
};

struct CB_NOTIFY4args {
        stateid4    cna_stateid;
        nfs_fh4     cna_fh;
        notify4     cna_changes<>;
};

xdrgen is supposed to omit that bounds check. Some of the Jinja2
templates handle that correctly, but a few are incorrect and leave
the bounds check in place with a maximum of zero, which causes
encoding/decoding of that type to fail unconditionally.

Reported-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: chucklever

tools/net/sunrpc/xdrgen/templates/C/pointer/encoder/variable_length_array.j2

@@ -2,8 +2,10 @@
 {% if annotate %}
 	/* member {{ name }} (variable-length array) */
 {% endif %}
+{% if maxsize != "0" %}
 	if (value->{{ name }}.count > {{ maxsize }})
 		return false;
+{% endif %}
 	if (xdr_stream_encode_u32(xdr, value->{{ name }}.count) != XDR_UNIT)
 		return false;
 	for (u32 i = 0; i < value->{{ name }}.count; i++)

tools/net/sunrpc/xdrgen/templates/C/struct/encoder/variable_length_array.j2

@@ -2,8 +2,10 @@
 {% if annotate %}
 	/* member {{ name }} (variable-length array) */
 {% endif %}
+{% if maxsize != "0" %}
 	if (value->{{ name }}.count > {{ maxsize }})
 		return false;
+{% endif %}
 	if (xdr_stream_encode_u32(xdr, value->{{ name }}.count) != XDR_UNIT)
 		return false;
 	for (u32 i = 0; i < value->{{ name }}.count; i++)

tools/net/sunrpc/xdrgen/templates/C/union/decoder/variable_length_array.j2

@@ -4,8 +4,10 @@
 {% endif %}
 		if (xdr_stream_decode_u32(xdr, &count) < 0)
 			return false;
+{% if maxsize != "0" %}
 		if (count > {{ maxsize }})
 			return false;
+{% endif %}
 		for (u32 i = 0; i < count; i++) {
 			if (xdrgen_decode_{{ type }}(xdr, &ptr->{{ name }}.items[i]) < 0)
 				return false;