scripts/unit-test: Prevent duplicate deps from being checked

Our code will treat this as a cycle if duplicate dependencies are passed
into our dependency builder loop. In the future if we support multiple
build systems it is possible that we will find duplicate dependencies
and need to handle that.

Change-Id: I3b52d6ce646d2ebf0ba1b23b85eb940408d5b9e8
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/scripts/unit-test.py b/scripts/unit-test.py
index c404d22..d51bdec 100755
--- a/scripts/unit-test.py
+++ b/scripts/unit-test.py
@@ -15,6 +15,7 @@
 import argparse
 import multiprocessing
 import re
+import sets
 import platform
 
 
@@ -365,7 +366,7 @@
     pkg_deps = []
     pkg_deps += get_autoconf_deps(pkgdir)
 
-    for dep in pkg_deps:
+    for dep in sets.Set(pkg_deps):
         if dep in cache:
             continue
         # Dependency package not already known