Correct wxFontMapper tables for Big-5, Shift-JIS and GB2312 encodings.

Correct wxFontMapper tables for Big-5, Shift-JIS and GB2312 encodings.

As wxFONTENCODING_{BIG5,SHIFT_JIS,GB2312} are only synonyms for the other
encoding constants, we must append the corresponding names to the array of
names for the real encoding value instead of having the (never used) separate
entries for them in the names array.

Closes #13164.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67644 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775