[Fontconfig] Fontconfig cache file update fails on Windows (also Cygwin)

[Masamichi Hosoda]

>> But, most Windows applications have their own fontconfig cache
>> directories
>> unlike linux applicatons.
>> In this case, there is no conflict with other applications
>> even if without locking.
>>   
> ---
>    Actually, that's a problem -- I wouldn't rely on that behavior
> staying that way.  It can take several minutes to generate a large
> font cache -- and doing that for each program would make things
> even worse.
> 
> 
>> fontconfig 2.11.1 does not lock the cache while updating it.
>> It works fine on Windows.
>>   
> ----
>    Yeah... just because it works right in isolation doesn't mean
> it will work right when multiple apps are trying to update it.

Current fontconfig takes several minutes each time
a application is started up for cache updating.

With my patch, as long as there is not multiple access,
the cache update succeeds with one time.

It is better that there is a possibility of success
rather than a way that does not succeed at all, in my humble opinion.