unit-test: support install process in cmake

This change allows cmake-based project to install the
executable/library/configuration to the right directory.

Tested:
Manually run the commands below in the docker.
```
$ sudo cmake --install .
-- Install configuration: ""
-- Installing: /usr/local/lib/xxx.so
-- Installing: /usr/local/include/xxx.h
-- Installing: /usr/local/bin/xxx_tool
```

Change-Id: Ica9f0c26c57baca5d46067c1bb55ecccc2d8fc58
Signed-off-by: Michael Shen <gpgpgp@google.com>
diff --git a/scripts/unit-test.py b/scripts/unit-test.py
index 5b98f1e..664e7ec 100755
--- a/scripts/unit-test.py
+++ b/scripts/unit-test.py
@@ -774,7 +774,7 @@
         )
 
     def install(self):
-        pass
+        check_call_cmd("sudo", "cmake", "--install", ".")
 
     def test(self):
         if make_target_exists("test"):