Cacao support for OpenJDK7

[David Flamme]

Hello,

I managed to compile and run cacao against OpenJDK7 on x86_64 at least 
on a "Hello World" level. Now I have some questions and want to point 
out what needs to be done in icedtea to compile the whole thing out of 
the box with cacao.

First of all, the cacao branch of what I did so far can be found here:
http://mips.complang.tuwien.ac.at/hg/cacao/rev/30edcde287d9

The biggest problem on the side of icedtea7 is, that you check not only 
the existence of libjsig.so, you also check if its not fake by using nm. 
What I do is copying a working version from my openjdk installation to 
the expected location, so the build won't complain but actually I have 
no clue whats going on there. JamVM probably has the same problem, so I 
mostly hope for a good suggestion from your side, what should be done here.

Then while replacing the hpi functionality I stumbled upon 
NO_INTERRUPTIBLE_IO, which would save me implementing a lot of 
multithreading support, if i can just expect its true. Can you tell me a 
bit about that issue?

It would be great if somebody could test the changeset or at least give 
me some hints.

best regards
    david