ext/nkf/nkf-utf8/nkf.c: Backport #2953 [ruby-dev:40606]; change nkf_char buffer in numchar_getc() size form 8 to 10 to avoid potential for a segfault.
test/nkf/test_nkf.rb: Added a test for the change.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8_6@28242 b2dd03c8-39d4-4d8f-98ff-823fe69b080e