Linux will do it for us but not NetBSD. That is, if foo is an executable
that prints the path /proc/self/exe points to, on Linux one gets:

$ ./foo
/tmp/foo
$ ln -s foo bar
$ ln -s bar babar
$ /tmp/babar
/tmp/foo

But on NetBSD one gets instead:

$ ./foo
/tmp/./foo
$ ln -s foo bar
$ ln -s bar babar
$ /tmp/babar
/tmp/babar

Fully dereferencing /proc/self/exe is necessary to be able to run both
32 and 64 bit executables from the build tree.
Signed-off-by: Francois Gouget <fgouget@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>