apphelp: add a stub for SdbInitDatabase

[Hans Leidekker]

On Sun, 2014-03-30 at 14:36 -0700, Austin English wrote:
> +PDB WINAPI SdbInitDatabase(DWORD flags, LPCSTR path)
> +{
> +    FIXME("stub: %u %s\n", flags, debugstr_a(path));
> +    SetLastError(ERROR_CALL_NOT_IMPLEMENTED);
> +    return NULL;
> +}

Return type should be HSDB. Please trace flags in hex.