Including cert store location for test runner.

This helps to avoid bad interactions between tests that rely
on the "java.home" property for different things. Preferences
tests tend to change it (to the writable temp directory), but
the certs tests fall back to it for the trust store.

See also TrustManagerFactoryImpl.java.
diff --git a/run-core-tests b/run-core-tests
index 70ab320..134a032 100755
--- a/run-core-tests
+++ b/run-core-tests
@@ -25,6 +25,10 @@
 mkdir $tmp
 chmod 777 $tmp
   
-exec dalvikvm -Duser.language=en -Duser.region=US -Djava.io.tmpdir=$tmp \
+exec dalvikvm \
+     -Duser.language=en \
+     -Duser.region=US \
+     -Djava.io.tmpdir=$tmp \
+     -Djavax.net.ssl.trustStore=/system/etc/security/cacerts.bks \
      -classpath /system/framework/core-tests.jar \
      -Xmx64M com.google.coretests.Main "$@"