[PATCH] fix [[ -t X ]] segfault

[Grisha Levit]

Since the change that made `test -t FD' report an error for non-numeric
values of FD:

$ [[ -t X ]]
bash: [[: X: integer expected
Segmentation fault

Below patch wraps all [[ test execution in a new function that provides
a jump target and returns an exit status usable directly by the
cond_node code -- so the above now has an exit status of 2 like the test
builtin.

0001-fix-t-X-segfault.patch
Description: Text Data