Windows-1252 was sometimes being referred to as ASCII or ANSI
in Dolphin, which is incorrect. ASCII is only a subset of
Windows-1252, and ANSI is (rather improperly) used in Windows
to refer to the current code page (which often is 1252 on
Western systems, but can also be something entirely different).

The commit also replaces "SJIS" with "Shift JIS". "SJIS"
isn't misleading, but "Shift JIS" is more commonly used.