bug#15260: cannot build in a directory with non-ascii characters

[Glenn Morris <rgm@gnu.org>]

Eli Zaretskii wrote:

> It requires too much setup on my part (this cannot be simulated on
> Windows without too much hassle).

Sorry, I assumed you could build on fencepost. I'm expecting multiple
points of failure, so this might not be an efficient process...

The first time, I was trying an out-of-tree build in a non-ascii build
directory, but still with ascii srcdir. Using an in-place build in a
non-ascii directory fails to even start temacs (this is with or without
your patch):

    Warning: arch-independent data dir
    `/tmp/EMACS/share/emacs/24.3.50/etc/': No such file or directory
    Error: charsets directory not found:
    /tmp/EMACS/share/emacs/24.3.50/etc/charsets
    Emacs will not function correctly without the character map files.
    Please check your installation!
    make[1]: *** [bootstrap-emacs] Error 1

/tmp/EMACS was my install --prefix. It's not supposed to exist until
after installation, but the code that tries to find etc/ is presumably
mistakenly concluding that srcdir/etc does not exist and that it must be
running installed.