LoggingPrintStream: Make visible for testing

The class must be public to avoid test issues. If the class is
package-private, the test would have to be in the boot class-
path:

 Rejecting re-init on previously-failed class java.lang.Class<com.android.internal.os.LoggingPrintStreamTest$TestPrintStream>: java.lang.IllegalAccessError: Class com.android.internal.os.LoggingPrintStream extended by class com.android.internal.os.LoggingPrintStreamTest$TestPrintStream is inaccessible (declaration of 'com.android.internal.os.LoggingPrintStreamTest$TestPrintStream' appears in /data/app/com.android.frameworks.coretests-SD7GJmYE507ACoE9gu2mnw==/base.apk)
   at java.lang.Object java.lang.reflect.Constructor.newInstance0(java.lang.Object[]) (Constructor.java:-2)
   at java.lang.Object java.lang.reflect.Constructor.newInstance(java.lang.Object[]) (Constructor.java:334)
   at junit.framework.Test junit.framework.TestSuite.createTest(java.lang.Class, java.lang.String) (TestSuite.java:61)

Test: m
Test: runtest -x frameworks/base/core/tests/coretests/src/com/android/internal/os/LoggingPrintStreamTest.java
Change-Id: I26cead7954cf4309c8b3e16994c35a3f4a9eb798