test: Add an overall test runner

Add a new test runner that will eventually be able to run any test. For
now, have it run the 'command' unit tests, so that the functionality in
cmd_ut_category() moves into it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/Makefile b/test/Makefile
index 932e517..5cd284e 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -2,6 +2,8 @@
 #
 # (C) Copyright 2012 The Chromium Authors
 
+obj-y += test-main.o
+
 ifneq ($(CONFIG_$(SPL_)BLOBLIST),)
 obj-$(CONFIG_$(SPL_)CMDLINE) += bloblist.o
 obj-$(CONFIG_$(SPL_)CMDLINE) += bootm.o