mruby/mruby — pull request #1642 by h2so5 (2014-01-05 10:21:08+00:00)
Title: remove unneeded ERR_PC_SET

This ERR_PC_SET seems to make wrong backtrace.

```ruby
def a
begin
raise ""
ensure
end
end
a
```
```
trace:
[2] test.rb:5:in Object.a
[0] test.rb:7
test.rb:3: RuntimeError
```
```ruby
begin
raise ""
ensure
end
```

```
trace:
[1] test.rb:4
test.rb:4: RuntimeError
```