test: Add some tests for kconfig.h

The macros in this file are a little confusing and we currently have no
tests to check that they work as expected.

Add some tests which check the macros in C code. Add a few tests which
check that the build errors are generated correctly too, using buildman's
-a option.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/Makefile b/test/Makefile
index 1dfd567..1787736 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -17,6 +17,9 @@
 obj-$(CONFIG_$(SPL_)UT_COMPRESSION) += compression.o
 obj-y += dm/
 obj-$(CONFIG_FUZZ) += fuzz/
+ifndef CONFIG_SANDBOX_VPL
+obj-$(CONFIG_UNIT_TEST) += lib/
+endif
 obj-$(CONFIG_$(SPL_)CMDLINE) += print_ut.o
 obj-$(CONFIG_$(SPL_)CMDLINE) += str_ut.o
 obj-$(CONFIG_UT_TIME) += time_ut.o
@@ -25,7 +28,6 @@
 ifeq ($(CONFIG_SPL_BUILD),)
 obj-$(CONFIG_UNIT_TEST) += boot/
 obj-$(CONFIG_UNIT_TEST) += common/
-obj-$(CONFIG_UNIT_TEST) += lib/
 obj-y += log/
 obj-$(CONFIG_$(SPL_)UT_UNICODE) += unicode_ut.o
 endif