RFC: Adding a check to the top level configure script for a binary-mounted cygwin-hosted build directory

[DJ Delorie]

> Are the problems described in PR 4334 also present when building
> under MinGW or DJGPP ?  If not, then we can keep this new autoconf
> test as a Cygwin specific test.

I don't have a djgpp build tree at the moment, but djgpp is like
*always* having text mounts.  So, you can simulate it with a cygwin
install where everything is text mounted.  However, DJGPP's tools know
about CR/LF so it may not expose this "bug".

> If those problems are also present then I would agree with you that
> we need to fix the binutils build process.

IMHO the bug is that cygwin's bash isn't dealing with `` line endings
properly.  It's the responsibility of the shell to strip trailing line
endings (1003.2-1992 3.6.3, although it doesn't mention
platform-specific line endings) during command substitution.

Also, cygwin's bash should allow CR/LF pairs as word delimiters during
splitting, if it doesn't already.  Cygwin supports mixed mounts, it
needs to deal with the ramifications itself.