configure check for sys/mman.h

[Tom Tromey]

>>>>> "Michael" == Michael Koch <konqueror@gmx.de> writes:

Michael> I've digged a little bit more and found a "better" solution using an 
Michael> autoconf feature. Please review and comment on this.

Michael> We will need mmap very soon now for java.nio.

This is fine, please check it in.

I've been putting all the nio stuff into 3.3 since, thus far, it has
been low risk, and it lets people at least compile their nio-using
programs against libgcj.

I'd like to ship at least an api-compatible nio in 3.3.  Whether it
really works is another question.  I think I'm going to hold off
putting this patch into 3.3, at least for the time being.

We can always put it in a bit later, either for 3.3.1 or for 3.3 if it
slips (as seems likely).  Also it depends on how well nio is working
in the near future.

Tom