Remove a reference to an obsolete Bouncycastle keystore file.

Without this, some SSL code fails with an exception:
java.io.FileNotFoundException: /system/etc/security/cacerts.bks: open failed: ENOENT (No such file or directory)
at libcore.io.IoBridge.open(IoBridge.java:410)
at java.io.FileInputStream.<init>(FileInputStream.java:78)
at java.io.FileInputStream.<init>(FileInputStream.java:105)
at org.apache.harmony.xnet.provider.jsse.DefaultSSLContextImpl.getTrustManagers(DefaultSSLContextImpl.java:115)
at org.apache.harmony.xnet.provider.jsse.SSLContextImpl.<init>(SSLContextImpl.java:71)
at org.apache.harmony.xnet.provider.jsse.OpenSSLContextImpl.<init>(OpenSSLContextImpl.java:34)
at org.apache.harmony.xnet.provider.jsse.DefaultSSLContextImpl.<init>(DefaultSSLContextImpl.java:59)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1319)
at java.security.Provider.newInstance(Provider.java:989)
... 15 more
Caused by: libcore.io.ErrnoException: open failed: ENOENT (No such file or directory)
at libcore.io.Posix.open(Native Method)
at libcore.io.BlockGuardOs.open(BlockGuardOs.java:98)
at libcore.io.IoBridge.open(IoBridge.java:393)
... 24 more

Change-Id: I631a8ee3f5b3e8c0e1caf43e85673ef77500b579