Add encoding-test datafiles to svn:ignore:

EUC-CN.TXT
CP936.TXT
BIG5HKSCS.TXT
CP932.TXT
EUC-JP.TXT
SHIFTJIS.TXT
EUC-JISX0213.TXT
SHIFT_JISX0213.TXT
CP949.TXT
EUC-KR.TXT
JOHAB.TXT
BIG5.TXT
CP950.TXT
NormalizationTest-3.2.0.txt