gnu: jamvm: Fix to work with current gcc and glibc.

* gnu/packages/java.scm (jamvm)[source]: Add patch.
(jamvm-1-bootstrap)[native-inputs]: Remove.
* gnu/packages/patches/jamvm-2.0.0-disable-branch-patching.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

Signed-off-by: Marius Bakke <marius@gnu.org>