java: Use optimization level '-O3'
java: Use optimization level '-O3'

There is no '-O6'. It is interpreted as '-O3' by GCC but rejected
by Clang.

Signed-off-by: Jussi Virtanen <2a7e40f91a3be32dfb7e35af6e476a252ebdb4f3@gmail.com>

penberg/pstore,penberg/pstore,penberg/pstore,penberg/pstore