[resend] Allow use of MAP_TRYFIXED for better mmap()

[Jon Bright]

Huw D M Davies wrote:

> It's available on the machine that the binary is compiled on sure, but
> what about the machine of a friend/customer who you've shipped the
> binary to?  Just because you have the new kernel feature on your build
> machine doesn't mean that everybody else does.  If you test at
> run-time you avoid these problems.

I believe Todd's point is that the build he's compiling won't work with 
any libc/kernel combination older than the one he's building with 
*anyway*.  So for NetBSD, there'll be a build built on an ancient 
machine, which will work pretty much everywhere and a build built on a 
newish machine, which will have this define.  If <random-NetBSD-Box> can 
run Todd's binary *at all*, then it's also guaranteed to have the 
facility his define's checking for.

-- 
Jon Bright
Silicon Circus Ltd.
http://www.siliconcircus.com