setup - inilint & building on cygwin

[Robert Collins]

Just an update:
1) inilint, the setup.ini validator is coming along. It can be enabled
via --enable-inilint on the configure line. It doesn't do anything just
yet though, but will build successfully.
2) I had a configure.in syntax error that was breaking on-cygwin builds.
That has been corrected.

In aid of 1), the io_streams code now dynamically registers the
providers - ie file:// and cygfile://. Pavel - this will affect your
patch (hopefully by making it simpler).

I'm considering changing cygfile:// to be posixfile://, for clarity -
what you do folk think?

Anyway, back to inilint, I'll be adding a new file:// provider that uses
the standard <iostreams> calls, so it should build on anything, and be
constrained purely by the host system's path syntax. It may not have the
full complement of remove/link etc available (for obvious reasons).

The last step for inilint is a check-only IniDBBuilder class, and then
we'll have the first setup.exe derived tool.

Woohoo!

Rob