Fix crashing when picking language

[scx]

Aegisub crashes immediately after selecting any language from the end of the list (above the 100th position).
This is because it can support no more than 100 languages.
This patch extends this limit up to 1000 languages (locales).

Fixes #131

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Test results from my system.

Number of dictionaries:

$ find /usr/share/myspell/ -xtype f -iname '*.dic' -exec printf %.0s. {} + | wc -m
242

Number of thesaurus:

$ find /usr/share/myspell/ -xtype f -iname '*.aff' -exec printf %.0s. {} + | wc -m
242

Number of languages:

$ cat <( find /usr/share/myspell/ -xtype f -iname '*.dic' -exec printf %.0s. {} + | wc -m ) <( find /usr/share/myspell/ -xtype f -iname '*.aff' -exec printf %.0s. {} + | wc -m ) | sort -nr | head -n 1
242

Number of locales:

locale -a | wc -l
791

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See also:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=935724#10
https://bugs.launchpad.net/ubuntu/+source/aegisub/+bug/1841381/comments/2