classpath: only allow on supported architectures

classpath: only allow on supported architectures

In commit a75ab1fc1dcc7eee8668b1c3c19b703f1390b2cd ("package/classpath:
Don't depend on jamvm"), we removed the dependency of classpath on
jamvm. Since jamvm is only available for a reduced set of architectures,
classpath could until this commit until be built on those architectures.

However, now that this dependency has been removed, classpath can
potentially be built for all architectures supported by Buildroot, even
though it doesn't support all of them.

Since adding support for additional architectures in classpath doesn't
make much sense, because classpath is in Buildroot only usable with
JamVM anyway, and JamVM is only available for a small set of
architectures, this commit simply makes classpath available on the
architectures that it supports.

By doing so, it also removes the or1k support patch which was added by
commit f12a146f817c8ef07a7d41a31a5336b5ef6a96e8, since anyway or1k is
not supported by JamVM.

Fixes:

  http://autobuild.buildroot.net/results/55eb89f89e96b94a821778bc18ed844af08b7460/
  (classpath on microblaze)

  http://autobuild.buildroot.net/results/279dd731bd9ecf5f9d54bda3715caeaa7cbcdbb3/
  (classpath on nios2)

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>