Update tools/java submodule (JAVA8_HOME)
Update tools/java submodule (JAVA8_HOME)

* tools/java 0b6ecbeb90...a2fe67fd42 (1):
  > build_reloc.sh: set JAVA8_HOME if not already set

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla