Fix Gecko codes loading

[Itrimel]

Fixes https://bugs.dolphin-emu.org/issues/11809

I found on my system (Archlinux) that using a locale with UTF-8 was breaking loading of Gecko codes. Hopefully forcing the C locale on this string stream should be enough without breaking it on other systems.

[JosJuice]

Do we know why this fixes it? It doesn't intuitively make sense to me.

[jordan-woyak]

FYI, The DownloadCodes function in this file also needs to be fixed.
Actually, downloading seems to work but the codes are displayed incorrectly..

I can reproduce the problem using LANG=fr_FR.UTF-8 (en_US.UTF-8 works fine).

[Itrimel]

While searching where this behavior could come from, I stumbled upon this :
while using this commit (Itrimel@b9844e5) on master and the locale fr_FR.UTF-8, the second part of all codes (which was before 00000000) will turn into a number which can be changed, among other things, by adding or removing comments from the source file (I typically get something around 00007f50).

So ... I am very lost about the true origin of this bug ...

[jordan-woyak]

Okay, apparently certain locales allow spaces within a single formatted number.
e.g. "1 2 3" is read as "123" even when reading decimal numbers.

Both GeckoCode values are read as a single 64 bit hex value which overflows causing the issue.

This is horrible. We probably assume formatted number input does not cross white space throughout dolphin.

[Itrimel]

Well that's bad ... I can also fix DownloadCodes (so that the display just after download works), but if there are more places to fix I think it would be best for you to take over.

[Itrimel]

Updated to better reflect jordan-woyak's findings in the comments and the commit message, and to add the fix to DownloadCodes function

[jordan-woyak]

In the future we should probably stop parsing things with stringstreams but I think this is a good quick fix for now to fix Gecko Codes.