Remove unused private put* methods from DirectByteBufferR

There are 6 private methods in java.nio.DirectByteBufferR class which are unused:

    private ByteBuffer putChar(long a, char x)
    private ByteBuffer putShort(long a, short x)
    private ByteBuffer putInt(long a, int x)
    private ByteBuffer putLong(long a, long x)
    private ByteBuffer putFloat(long a, float x)
    private ByteBuffer putDouble(long a, double x)

This methods are only called from fragments where calls are guarded by #if[rw] condition.