initial client side unicode support (needed for netapp filer)

I've currently got this code disabled by default as it is
incomplete. You enable it by setting a USE_UNICODE environment
variable. Once the support is complete this check will be removed and
the CAP_UNICODE capability bit will be the sole determination of
whether the client library code uses unicode

right now I have converted session_setup and tconx. I will do more fns
over the next few days.

see clistr.c for the new client side string interface. Luckily it
tends to make the code smaller and neater while adding unicode
support.

source/include/client.h

@@ -29,6 +29,12 @@
    will be a multiple of the page size on almost any system */
 #define CLI_BUFFER_SIZE (0xFFFF)
 
+
+/* clistr flags - see clistr.c */
+#define CLISTR_TERMINATE 1
+#define CLISTR_CONVERT 2
+#define CLISTR_UPPER 4
+
 /*
  * These definitions depend on smb.h
  */