compile.c: store IDs as Symbols

* compile.c (iseq_set_arguments): store local variable IDs in
  temporary list as Symbols.  previously these are stored as
  Fixnums to prevent from GC, but IDs of dynamic symbols can
  exceed Fixnum range and cause RangeError at inverting from
  Fixnum.  [ruby-dev:48564] [Bug #10266]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47648 b2dd03c8-39d4-4d8f-98ff-823fe69b080e