Sets the specified 64-bit long integer at the current
{@code writerIndex} in the Little Endian Byte Order and
increases the {@code writerIndex} by {@code 8}
in this buffer.
If {@code this.writableBytes} is less than {@code 8}, {@link #ensureWritable(int)}
will be called in an attempt to expand capacity to accommodate.
Sets the specified 64-bit long integer at the current {@code writerIndex} in the Little Endian Byte Order and increases the {@code writerIndex} by {@code 8} in this buffer. If {@code this.writableBytes} is less than {@code 8}, {@link #ensureWritable(int)} will be called in an attempt to expand capacity to accommodate.