buildroot

classpath: enable on sparc and sparc64

GNU classpath builds fine on sparc and sparc64 architectures. So
we allow building it there to be consistent with the naming of
BR2_PACKAGE_CLASSPATH_ARCH_SUPPORTS.

Signed-off-by: Marcus Hoffmann <m.hoffmann@cartelsol.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>