add unittests for the minijail0 cli

Bug: None
Test: `make check` passes

Change-Id: I927a609453881e045e07013b7cca8594cc5e972c
diff --git a/.gitignore b/.gitignore
index 8713a1e..f538f37 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,6 +10,7 @@
 # Executables when compiling in-tree.
 /libminijail_unittest
 /minijail0
+/minijail0_cli_unittest
 /syscall_filter_unittest
 /system_unittest
 /util_unittest