Ruby

string.c: check just before modification

• string.c (rb_str_chomp_bang): check if modifiable after checking
  an argument and just before modification, as it can get frozen
  during the argument conversion to String.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59112 b2dd03c8-39d4-4d8f-98ff-823fe69b080e