unit-test: clean up evironment after Hush tests

Delete the temporary variables that are used to save unit-test results
from the environment after running the test. This prevents polluting
the environment, or growing it too much.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/test/command_ut.c b/test/command_ut.c
index 620a297..4f42056 100644
--- a/test/command_ut.c
+++ b/test/command_ut.c
@@ -65,7 +65,8 @@
 	run_command("if test " expr " ; then " \
 			"setenv " #name "_" #expected_result " y; else " \
 			"setenv " #name "_" #expected_result " n; fi", 0); \
-	assert(!strcmp(#expected_result, getenv(#name "_" #expected_result)));
+	assert(!strcmp(#expected_result, getenv(#name "_" #expected_result))); \
+	setenv(#name "_" #expected_result, NULL);
 
 	/* Basic operators */
 	HUSH_TEST(streq, "aaa = aaa", y);