* iconvdata/big5hkscs.c: Rewritten. Regenerate data from the
official file.
* iconvdata/TESTS: Add BIG5HKSCS entry.
* iconvdata/testdata/BIG5HKSCS: New file.
* iconvdata/testdata/BIG5HKSCS..UTF8: New file.
* iconvdata/big5.c (BODY for FROM_LOOP): Remove condition which is
always true.