Fix compilation using mingw.org's MinGW

[Pedro Alves]

On 4/18/19 6:20 PM, Pedro Alves wrote:
> On 4/18/19 4:36 PM, Eli Zaretskii wrote:
> 
>> MinGW64 no longer supports versions of Windows older than XP, but
>> mingw.org's MinGW does.  Since we load GetCurrentConsoleFont
>> dynamically at run time, and have code for when the load fails, it
>> makes sense to not assume XP at compile time.  The patch below does
>> that.  OK to push (with the pertinent ChangeLog entry)?
> 
> Didn't we drop support for < XP some time ago?
> 

>From gdb/NEWS:

~~~~~~~~~~~~
* Removed targets

GDB no longer supports native debugging on versions of MS-Windows
before Windows XP.
~~~~~~~~~~~~

So shouldn't we instead be setting _WIN32_WINNT to some
appropriate number?

Thanks,
Pedro Alves