Strange variable definition for std.ascii.newline

[Herringway]

Currently, the definition of std.ascii.newline has some strange issues.
The POSIX version is duplicated, while the windows version is wrongly typed as void.

In case something changes, the current definition is displayed as:

immutable(char[]) newline = "\x0a";
immutable(char[]) newline = "\x0a";
void newline = "\x0d\x0a";

while the code for std.ascii.newline is:

/// Newline sequence for this system.
version(Windows)
    immutable newline = "\r\n";
else version(Posix)
    immutable newline = "\n";
else
    static assert(0, "Unsupported OS");