Improve -verbose:jni.

Improve -verbose:jni.

The old output just told you what functions were being called and made no
attempt to show you their arguments. The new output was sufficient to debug
an actual problem with an app we don't have the source to.

Still to do:
0. an easier way for third-party developers to enable this.
1. the primitive type arguments to SetIntField and so forth.
2. return values.

A few examples of the new output...

A decoded jclass:
  JNI: libcore.io.Posix.readBytes called IsInstanceOf((JNIEnv*)0x9618470, 0x28100015, java.lang.Class<byte[]>)

A decoded jfieldID:
  JNI: libcore.io.Posix.ioctlInt called GetIntField((JNIEnv*)0x9618470, 0x5cb00011, java.io.FileDescriptor.descriptor)

A decoded jmethodID (the FileDescriptor constructor):
  JNI: libcore.io.Posix.open called NewObject((JNIEnv*)0x9780480, java.lang.Class<java.io.FileDescriptor>, java.io.FileDescriptor.<init>()V, ...)

A const char*:
  JNI: libcore.io.Posix.getsockoptLinger called NewStringUTF((JNIEnv*)0x9618470, "getsockopt")

A jint release mode:
  JNI: libcore.io.Posix.writeBytes called ReleaseByteArrayElements((JNIEnv*)0x9780480, 0x2700009, (void*) 0xf5f623c4, JNI_ABORT)

The -verbose:jni option now turns on a bit more output about JNI_OnLoad calls
but no longer causes any logging of calls to JNIEnv or JavaVM functions. The
old -Xjnitrace: option has been extended to enable this new tracing for the
native methods that it covers. They go very well together for debugging
purposes.

I've also made us a bit more verbose if we fail to initialize. In the longer
term I think we want to just abort if we hit any failure during startup, but
my extra logging will save us a bit of time next time we have one of these
failures (this one was caused for me by only having one half of the finalizer
watchdog change; I was missing the libcore side).

(Cherry pick of 6734b8224fb869c94e42e704ec03f2ce8483af2b from dalvik-dev.)

Change-Id: I69b7620b20620e9f06576da244520d9d83f89ab8