We keep all of the code page tables in the module
GHC.IO.Encoding.CodePage.Table.  That file was generated automatically
by running codepages/MakeTable.hs; more details are in the comments at the
start of that script.

Storing the lookup tables adds about 40KB to each statically linked executable;
this only increases the size of a "hello world" program by about 7%.

Currently we do not support double-byte encodings (Chinese/Japanese/Korean), since
including those codepages would increase the table size to 400KB.  It will be
straightforward to implement them once the work on library DLLs is finished.