merge revision(s) 44411: [Backport #9295]

	* vm_insnhelper.c (argument_error): insert dummy frame to make
	  a backtrace object intead of modify backtrace string array.
	  [Bug #9295]

	* test/ruby/test_backtrace.rb: add a test for this patch.
	  fix test to compare a result of Exception#backtrace with
	  a result of Exception#backtrace_locations.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@44431 b2dd03c8-39d4-4d8f-98ff-823fe69b080e