[Issue 19290] immutable associative array corruption with -m64 and MinGW

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19290

--- Comment #1 from Basile B. <b2.temp at gmx.com> ---
main.d for the reproduction

```
void main()
{
    import dparse.parser, dparse.ast, dparse.lexer, dparse.rollback_allocator;
    import std.file;

    class Visitor : ASTVisitor {}

    LexerConfig config;
    StringCache cache = StringCache(16);
    RollbackAllocator rba;

    auto src = readText(r"libdparse\src\dparse\parser.d");
    auto tok = getTokensForParser(src, config, &cache);
    auto mod = parseModule(tok, "stdin", &rba);
    auto vis = new Visitor;
    vis.visit(mod);
}
```

--