Add pax flags to java binary

[el-chogo]

Add pax flags so systems with grsec patchset may run jetty without any further modification (hopefully).

[md5]

@clinoge Thanks for bringing up this issue, but I wonder if it would make more sense for these flags to be set in the java:*-alpine images instead of here.

Also, whether those flags are set in this image or in java, I'm not sure that we can rely on setfattr in official images yet, since my understanding is that AUFS didn't support extended attributes until quite recently.

If this approach works for your use case, it seems like you could easily call setfattr in an image derived from the jetty image. Others who need PaX support could do the same in their images (hopefully after seeing your approach documented in this PR).

[el-chogo]

Wow, that's actually true, I should've put that on java:*-alpine. Must've been really sleepy ;).

[md5]

Closing this request since it needs to happen in the java image if it can be done at all.