test: env: Add test framework for env

Add a new "env" subcommand to the ut command.

This will run unit tests on the env code. This should be targetable to
any device that supports the env features needed for the tests.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/Makefile b/Makefile
index 1cdc4a1..bc47d98 100644
--- a/Makefile
+++ b/Makefile
@@ -666,6 +666,7 @@
 libs-$(CONFIG_HAS_POST) += post/
 libs-y += test/
 libs-y += test/dm/
+libs-$(CONFIG_UT_ENV) += test/env/
 
 libs-y += $(if $(BOARDDIR),board/$(BOARDDIR)/)