Add a rule for android-common-ex tests in testrunner

Some tests were moved from frameworks/base 7 years ago (ag/54455),
but the rule was never added so they couldn't have been run with
testrunner.

Test: testClass can be run with "runtest -c testClass android-common-ex"
Bug: 62161211
Change-Id: Ie70f0fc32ceec59c3d89be75415adff34c1402ed
diff --git a/testrunner/test_defs.xml b/testrunner/test_defs.xml
index 75edadb..377f806 100644
--- a/testrunner/test_defs.xml
+++ b/testrunner/test_defs.xml
@@ -143,6 +143,12 @@
     coverage_target="framework"
     continuous="true" />
 
+<test name="android-common-ex"
+    build_path="frameworks/ex/common/tests"
+    package="com.android.common.tests"
+    coverage_target="framework"
+    continuous="true" />
+
 <test name="ex-variablespeed"
     build_path="frameworks/ex/variablespeed/tests"
     package="com.android.ex.variablespeed.tests"