* compile.c (iseq_compile_each): out of range NTH_REF is always
	  nil.

	* parse.y (parse_numvar): check overflow of NTH_REF and range.
	  [ruby-core:69393] [Bug #11192]

	* util.c (ruby_scan_digits): make public and add length parameter.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@51122 b2dd03c8-39d4-4d8f-98ff-823fe69b080e