Add pt-pt alias for pt language flag

[waldyrious]

Since Brazilian Portuguese is the globally dominant variety of Portuguese (in terms of number of speakers and cultural influence) similar to how American English is for English, it is common for people to use a pt-pt language code to specifically refer to European Portuguese.

This commit therefore adds an alias pt-pt -> pt, similar to the existing en-gb -> en alias for English (United Kingdom). (correction: I misread the language/en.svg -> gb.svg link. An en-gb -> en alias does not actually exist at this point.)

Despite the apparent redundancy, the pt-pt code is actually used in practice, and indeed has an IETF language tag (pt-PT) and POSIX locale (pt_PT).

[HatScripts]

Good to know! As always, thanks for the contribution.

[waldyrious]

This symlink may be useful in the future, in case a flag for the Portuguese language (encompassing all its varieties) becomes established and is adopted for the language/pt.svg file, in which case language/pt-pt.svg could continue to point to the flag of Portugal, and would be added to the Gallery page as "Portuguese (Portugal)".

In fact, there is already a potential candidate for a more generic flag image for Portuguese — specifically, the CPLP flag:

I'm not sure that would be broadly recognizable as "Portuguese" by most speakers, since almost everywhere the flags of Portugal or Brazil (or a mix thereof) are used in language selectors, etc; but if we did want to encourage the decoupling of language flags from the countries where they originated them, this could be an option to consider.