dix: rpcbuf: add rpcbuf_write_INT16()

Just a convenience wrapper for writing an INT16.
Technically it's really the same as CARD16, but we still need a typecast
in order to not getting a compiler warning on int signedness mismatch.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>

dix/rpcbuf_priv.h

@@ -169,6 +169,22 @@ Bool x_rpcbuf_write_CARD8(x_rpcbuf_t *rpcbuf, CARD8 value)
 Bool x_rpcbuf_write_CARD16(x_rpcbuf_t *rpcbuf, CARD16 value)
     _X_ATTRIBUTE_NONNULL_ARG(1);
 
+/*
+ * write a INT16 and do byte-swapping (when needed).
+ *
+ * allocate a region for INT16, write it into the buffer and do byte-swap
+ * if buffer is configured to do so (`swapped` field is TRUE).
+ *
+ * doesn't do any padding.
+ *
+ * @param rpcbuf    pointer to x_rpcbuf_t to operate on
+ * @param value     the CARD16 value to write
+ * @return          TRUE on success, FALSE on allocation failure
+ */
+static inline Bool x_rpcbuf_write_INT16(x_rpcbuf_t *rpcbuf, INT16 value) {
+    return x_rpcbuf_write_CARD16(rpcbuf, (CARD16)value);
+}
+
 /*
  * write a CARD32 and do byte-swapping (when needed).
  *