Dynamic Java installation path detection

https://github.com/yahoo/mdbm/blob/master/src/java/Makefile#L18-L19 causes Java wrapper compile error on machine that has a different Java installation like

/usr/lib/jvm/java-8-openjdk-amd64/include/ instead of /usr/lib/jvm/java/include and
/usr/lib/jvm/java-8-openjdk-amd64/jre/lib/amd64 instead of /usr/lib/jvm/java/jre/lib/amd64/

User have to manually replace/fix this

I can work on fixing it if needed. 😉