Add pre-release banner and adjust testsuite

Adding a banner indicating that this is a pre-release that offers
limited functionality.  Also mark all test directories as unreliable,
nd therefore all tests will be skipped for now until verifiable
functionality is available.

Orabug: 30619056
Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>

cmd/dtrace.c

@@ -928,6 +928,10 @@ main(int argc, char *argv[])
 
 	g_pname = basename(argv[0]);
 
+	/* Temporary banner. */
+	printf("DTrace %s [Pre-Release with limited functionality]\n",
+	       _DT_VERSION);
+
 	if (argc == 1)
 		return (usage(stderr));