[autoconf-conversion] Something to start with

[DJ Delorie]

The MMAP test is only useful if you can run the executable; it tests
to see if strncmp accesses memory beyond the string it's checking by
using mmap to make the next byte be outside its memory space.

I think it makes sense to at least get a few directories converted
(preferably different classes of directories: build, host, target,
etc) before we start submitting anything.  That way we'll have a
better warm-n-fuzzy that we've at least seen all the weird cases we're
going to encounter.

Let's at least not start with the one that triggers the most exception
cases ;-)