start a util unittest

Bug: None
Test: `make check` passes
Change-Id: I9a39bf72649f040b95be68a4fa8f799b6e7ead65
diff --git a/.gitignore b/.gitignore
index a121c9e..8713a1e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,6 +12,7 @@
 /minijail0
 /syscall_filter_unittest
 /system_unittest
+/util_unittest
 /parse_seccomp_policy
 
 # common.mk TEST().