Fixed org.simantics.lz4 to use bundle data area when running in OSGi

Previously org.simantics.lz4 would always extract the native LZ4 dynamic
library to java.io.tmpdir which is plain stupid. Now when running in
OSGi environment, we simply extract the file once to the data area and
reuse it from there.

Further development could even use the MD5 sum of the lz4 DLL to extract
every version of the DLL only once to java.io.tmpdir but I'm saving this
for later.

refs #7578

Change-Id: I50566999749b20cca6d56ab52e59101ec3a7b6f6