i2p: Build java service wrapper from source
i2p: Build java service wrapper from source

The most tricky part was the JAVA_TOOL_OPTIONS part.  `javah` simply
throws a NullPointerException if it cannot find a java compiler.  See
http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b27/javax/tools/ToolProvider.java#ToolProvider.getSystemJavaCompiler%28%29
on how that compiler is searched for.

SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs