Improve printf handling of size_t args

The %*s format takes two arguments, a precision length/width and
an actual string; the length is specified as a signed integer.
The size_t length field of the gss_buffer_desc type is an unsigned
type, which must be cast or otherwise converted to a signed type
to match the format string expectations.
I do not think that the length will approach SIZE_T_MAX in practice,
due to buffer constraints, so do not include handling for the
edge case.

There is a '%zu' format string for printing size_ts, but it is not
available everywhere (e.g., AIX).  Instead, use the
unsigned long long abomination.

src/appl/gss-sample/gss-server.c

@@ -893,7 +893,7 @@ showLocalIdentity(OM_uint32 *minor, gss_name_t name)
 
     major = gss_localname(minor, name, GSS_C_NO_OID, &localname);
     if (major == GSS_S_COMPLETE)
-        printf("localname: %-*s\n", localname.length, localname.value);
+        printf("localname: %-*s\n", (int)localname.length, localname.value);
     else if (major != GSS_S_UNAVAILABLE)
         display_status("gss_localname", major, *minor);
     gss_release_buffer(minor, &localname);

src/lib/rpc/auth_gssapi_misc.c

@@ -183,7 +183,7 @@ static void auth_gssapi_display_status_1(
 	  putc ('\n', stderr);
 	  if (misc_debug_gssapi)
 	      gssrpcint_printf("GSS-API authentication error %s: %*s\n",
-			       m, msg.length, (char *) msg.value);
+			       m, (int)msg.length, (char *) msg.value);
 	  (void) gss_release_buffer(&minor_stat, &msg);
 
 	  if (!msg_ctx)
@@ -296,8 +296,9 @@ bool_t auth_gssapi_unwrap_data(
      if (*major != GSS_S_COMPLETE)
 	  return FALSE;
 
-     PRINTF(("gssapi_unwrap_data: %d bytes data, %d bytes sealed\n",
-	     out_buf.length, in_buf.length));
+     PRINTF(("gssapi_unwrap_data: %llu bytes data, %llu bytes sealed\n",
+	     (unsigned long long)out_buf.length,
+	     (unsigned long long)in_buf.length));
 
      xdrmem_create(&temp_xdrs, out_buf.value, out_buf.length, XDR_DECODE);