added -sourcepath flags to javac so to work around some compilation prob...

I was getting this error when trying to build (after a fresh checkout of the repository)

    /usr/lib/jvm/default/bin/javac -g:none -deprecation com/etsy/net/UnixDomainSocket.java
    com/etsy/net/UnixDomainSocket.java:40: error: package JUDS does not exist
                jarFile = new File(JUDS.jarURL.toURI());
                                        ^
    com/etsy/net/UnixDomainSocket.java:199: error: cannot find symbol
            if (socketType == JUDS.SOCK_STREAM)
                              ^
      symbol:   variable JUDS
      location: class UnixDomainSocket
    2 errors
    Makefile:59: recipe for target 'com/etsy/net/UnixDomainSocket.class' failed
    make: *** [com/etsy/net/UnixDomainSocket.class] Error 1

This PR fixes this problem by ensuring that the current directory is sent as a source directory to `javac` and `javah`.