Add test framework for bmpblk_utility.

BUG=chromium-os:11742
TEST=manual

Check out sources, run:

  cd src/platform/vboot_reference
  make
  make runbmptests

It should pass.

Change-Id: I50ebdef26662e7446828315a3f5e2786624508b9

Review URL: http://codereview.chromium.org/6246150
diff --git a/Makefile b/Makefile
index 0d29bd5..d12639d 100644
--- a/Makefile
+++ b/Makefile
@@ -77,3 +77,6 @@
 
 rbtest:
 	$(MAKE) -C tests rbtest
+
+runbmptests:
+	$(MAKE) -C tests runbmptests