Incorrect copyright header in src/hotspot/os_cpu/linux_sparc/os_linux_sparc.cpp

The following file has an incorrect header format:

src/hotspot/os_cpu/linux_sparc/os_linux_sparc.cpp

   * Copyright (c) 1999, 20209, Oracle and/or its affiliates. All rights reserved.

The second year, YEAR should be "2020,"

You can verify the header is correct with make/scripts/lic_check.sh to make sure each file now passes.

The template is located at:
  make/templates/gpl-header
  make/templates/gpl-cp-header