Copy original_preg and fix a double-free
Copy original_preg and fix a double-free

- Make a copy of original_preg so the regular expression object is valid
when the error is constructed [*].
- Fix a double-free with preg in kyua_tap_try_parse_plan(..) (I fixed this
before on a different branch..).

[*] Submitted-by: jmmv
Sponsored-by: EMC / Isilon Storage Division

jmmv/kyua,rodrigc/kyua,jmmv/kyua,rodrigc/kyua,jmmv/kyua,jmmv/kyua,rodrigc/kyua,rodrigc/kyua